Mailpiece design: size, shape and machinability

What is the minimum letter size to mail?

A letter must be at least 3-1/2 inches high, 5 inches long and 0.007 inch thick to be mailable.5Publication 32: Glossary of Postal Termspage 135“For mailability, all mailpieces must be at least 0.007 inch thick. … For mailpieces 0.007 inch to 1/4 inch thick, the pieces must be at least 3-1/2 inches high and at least 5 inches long, except keys and identification devices.”USPS original A letter more than 6 inches long or 4-1/4 inches high must be at least 0.009 inch thick.6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“For pieces more than 6 inches long or 4-1/4 inches high, the minimum thickness is 0.009.”USPS original A single-piece First-Class Mail letter thinner than that pays the nonmachinable surcharge.6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Pieces not meeting the 0.009 thickness are subject to a nonmachinable surcharge under”USPS original7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original For automation compatibility, so automated equipment can scan and process it, a letter's aspect ratio, length divided by height, must be between 1.3 and 2.5.8Publication 32: Glossary of Postal Termspage 21“Mail that can be scanned and processed by automated mail processing equipment such as a barcode sorter.”USPS original9Publication 32: Glossary of Postal TermsPDF page 22“The dimension of a mailpiece expressed as a ratio of length (the direction parallel to the address) divided by height. … An aspect ratio between 1.3 and 2.5, inclusive, is required for automation compatibility.”USPS original A single-piece First-Class Mail letter outside that range still mails, with the nonmachinable surcharge.9Publication 32: Glossary of Postal TermsPDF page 22“For First-Class Mail letters, aspect ratio determines whether a nonmachinable surcharge applies.”USPS original7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Has an aspect ratio (length divided by height) of less than 1.3 or more than 2.5.”USPS original

What size envelope requires extra postage?

A single-piece First-Class Mail letter pays the nonmachinable surcharge when it has a nonmachinable trait, such as an aspect ratio under 1.3 or over 2.5.7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Has an aspect ratio (length divided by height) of less than 1.3 or more than 2.5.”USPS original A letter over 3.5 ounces pays flat prices, as does an envelope over a letter's size up to 15 by 12 inches and 3/4 inch thick.6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Not more than 3.5 ounces (First-Class Mail letter-size pieces over 3.5 ounces pay flat-size prices).”USPS original3Publication 32: Glossary of Postal TermsPDF page 92“A mailpiece that exceeds one of the dimensions for letter-size mail (11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick) but that does not exceed the maximum dimension for the mail processing category (15 inches long, 12 inches high, 3/4 inch thick).”USPS original10Publication 32: Glossary of Postal Termspage 85“First-Class Mail comprises six products: (a) single-piece letters/postcards, (b) presorted letters/ postcards (nonmachinable, machinable, and automation prices), (c) flats (single-piece, presorted, and automation prices), (d) parcels (retail, Commercial Base, and Commercial Plus prices), (e) outbound single-piece First-Class Mail International, and (f) inbound single-piece First-Class Mail International.”USPS original A larger piece is a parcel, and a large envelope that is rigid, nonrectangular or not uniformly thick pays parcel prices.11Publication 32: Glossary of Postal Termspage 157“(1) Mail that does not meet the mail processing category of letter-size mail or flat-size mail.”USPS original12Notice 123: Price List (effective October 4, 2026)“Large envelope-sized pieces that are rigid, nonrectangular, or not uniformly thick pay parcel prices.”USPS original As of October 4, 2026, the surcharge is $0.49, a 1-ounce stamped letter costs $0.82, and a 1-ounce large envelope costs $1.69.12Notice 123: Price List (effective October 4, 2026)“Notice 123 • Effective October 04, 2026 … Letters that meet one or more of the nonmachinable characteristics in DMM 101.1.2 are subject to the $0.49 nonmachinable surcharge. … 1 | $0.82 | 2 | 1.11 … 1 | $1.69 | 2 | 1.98”USPS original

What size envelopes can be mailed?

An envelope mails as a letter up to 11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick and 3.5 ounces.2Publication 32: Glossary of Postal TermsPDF page 118“A mail processing category that consists of letters and cards meeting minimum size standards and not exceeding the maximum letter-size mail dimensions of 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.”USPS original13Appendix C: ACS™ Product Code Information and Detailspage 5“Letters including post cards - that do not exceed any of the dimensions for letter-size mail (i.e., 111/2 inches long, 6-1/8 inches high, 1/4 inch thick up to 3.5 ounces)”USPS original A larger envelope is a flat, up to 15 inches long, 12 inches high and 3/4 inch thick, and it must be flexible.3Publication 32: Glossary of Postal TermsPDF page 92“A mailpiece that exceeds one of the dimensions for letter-size mail (11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick) but that does not exceed the maximum dimension for the mail processing category (15 inches long, 12 inches high, 3/4 inch thick). … Flat-size mail must also be flexible.”USPS original Mail that is neither a letter nor a flat is a parcel.11Publication 32: Glossary of Postal Termspage 157“(1) Mail that does not meet the mail processing category of letter-size mail or flat-size mail.”USPS original

How much is the USPS nonmachinable surcharge?

As of October 4, 2026, the nonmachinable surcharge is $0.49 a piece, added to a single-piece First-Class Mail letter with one or more nonmachinable traits.12Notice 123: Price List (effective October 4, 2026)“Letters that meet one or more of the nonmachinable characteristics in DMM 101.1.2 are subject to the $0.49 nonmachinable surcharge. … Notice 123 • Effective October 04, 2026”USPS original7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original Pieces mailed at the card price don't pay it.7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“Pieces mailed at the card price are not subject to the nonmachinable surcharge.”USPS original A shortpaid nonmachinable First-Class Mail letter goes back to the sender for more postage.14DMM 604: Postage Payment Methods and Refunds“Shortpaid nonmachinable First-Class Mail letters are returned to the sender for additional postage.”USPS original

What size postcards can be mailed?

A card mails at the First-Class Mail postcard price up to 4-1/4 inches high, 6 inches long and 0.016 inch thick.15Full-Service Certification Standardspage 57“All First-Class Post cards must not exceed 4-1/4 inches in height and 6 inches in length and 0.016 inches in thickness”USPS original Like any piece up to 1/4 inch thick, it must be at least 3-1/2 inches high and 5 inches long.5Publication 32: Glossary of Postal Termspage 135“For mailpieces 0.007 inch to 1/4 inch thick, the pieces must be at least 3-1/2 inches high and at least 5 inches long, except keys and identification devices.”USPS original A larger postcard pays First-Class Mail letter postage instead.16Publication 32: Glossary of Postal Termspage 173“A commercially produced and sold rectangular card designed for writing and mailing without an envelope and requiring First-Class Mail card or letter postage, depending on the dimensions.”USPS original

What envelope size can I mail with one stamp?

One Forever stamp pays the First-Class Mail single-piece price for a 1-ounce letter.14DMM 604: Postage Payment Methods and Refunds“Forever stamps are sold for the price of the current First-Class Mail single-piece 1-ounce letter price.”USPS original A letter is at most 11-1/2 inches long, 6-1/8 inches high and 1/4 inch thick.2Publication 32: Glossary of Postal TermsPDF page 118“A mail processing category that consists of letters and cards meeting minimum size standards and not exceeding the maximum letter-size mail dimensions of 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.”USPS original USPS also sells Forever stamps worth the additional-ounce price and the nonmachinable surcharge.14DMM 604: Postage Payment Methods and Refunds“The following Forever stamps will always be equal in value to the applicable price for the price category printed on them, at the time of use: … The current FCM additional-ounce price … FCM non-machinable surcharge price”USPS original

What is a TED-C letter?

A TED-C letter is a letter-size piece with a die-cut that extends past its conventional trailing edge, its left edge.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“TED-C mailpieces are letter-size pieces that have a die-cut that extends past the conventional trailing edge of the mailpiece.”USPS original18Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter PricesPDF page 1“Die-cut must be only on the trailing (left) edge.”USPS original Under Alternative Designs, these non-rectangular letters mail at automation letter prices.19PostalPro: Alternative Designs“The USPS and the mailing industry have worked together to create requirements that will allow for the mailing of non-rectangular TED-C letter-size pieces at the automation letter prices.”USPS original Only Full-Service First-Class Mail and USPS Marketing Mail letters with an Intelligent Mail barcode in the address block qualify.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Only Full-Service First-Class Mail letters and USPS Marketing … Mail® letters with an address block Intelligent Mail® barcode (IMb) that meet the TED-C physical standards are eligible for automation prices.”USPS original

Is pre-approval by USPS required to mail TED-C letters?

No: since February 1, 2023, mailers need no pre-approval from the Pricing and Classification Service Center to mail TED-C letters.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“No, as of February 1st, 2023, mailers are no longer required to obtain pre-approval from the Pricing & Classification Service Center (PCSC) to mail TED-C letters.”USPS original They may check a piece with the TED-C Letters Template.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Mailers may use the TED-C Letters Template, available on PostalPro at: https://postalpro.usps.com/alternative_designs/ted_c_template, to determine if their mailpiece meets USPS requirements for TED-C mailability.”USPS original USPS encourages mailers to send TED-C designs to a Mailpiece Design Analyst for review.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“However, mailers are encouraged to submit requests for TED-C design reviews to a Mailpiece Design Analyst at MDA@usps.gov.”USPS original

A mailpiece's dimensions, physical characteristics and weight set its mail processing category.1Publication 32: Glossary of Postal TermsPDF page 130“One of five designations for mail (letter-size mail, flat-size mail, machinable parcel, irregular parcel, and outside parcel), based on physical dimensions (height, length, and thickness), physical characteristics, and weight.”USPS original A letter is no larger than 11-1/2 by 6-1/8 inches and 1/4 inch thick.2Publication 32: Glossary of Postal TermsPDF page 118“A mail processing category that consists of letters and cards meeting minimum size standards and not exceeding the maximum letter-size mail dimensions of 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.”USPS original A flat is larger than a letter in one dimension, up to 15 by 12 inches and 3/4 inch thick.3Publication 32: Glossary of Postal TermsPDF page 92“A mailpiece that exceeds one of the dimensions for letter-size mail (11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick) but that does not exceed the maximum dimension for the mail processing category (15 inches long, 12 inches high, 3/4 inch thick).”USPS original Mail that is neither is a parcel, which USPS sorts as machinable or nonstandard.11Publication 32: Glossary of Postal Termspage 157“(1) Mail that does not meet the mail processing category of letter-size mail or flat-size mail.”USPS original20DMM 201: Commercial Mail, Physical Standards“USPS categorizes parcels into one of two mail-processing categories: machinable or nonstandard.”USPS original The irregular and outside parcels were earlier categories: USPS retired the irregular parcel, and the outside parcel became the nonstandard parcel.21Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 15“Updated processing categories – retired processing category Irregular (4) and changed Nonmachinable (5) to Nonstandard”USPS original22Postal Bulletin 22431: DMM Revision: Parcel Simplification (Dec 2015)“As a result, the Postal Service is taking the first step in this initiative by clarifying that the term “outside parcel” is a “nonmachinable parcel” in various sections of the DMM for consistency.”USPS original

Within each shape, a machinable piece fits the specifications and tolerances of USPS's mail processing equipment.23Publication 32: Glossary of Postal TermsPDF page 124“The physical capacity of a mailpiece to be sorted by mail processing equipment because its size, shape, configuration, and weight are within the specifications and tolerances of the equipment.”USPS original A nonmachinable piece is processed by hand and may pay a surcharge or a higher price.4Publication 32: Glossary of Postal Termspage 146“Such mail must be processed manually and may be subject to a surcharge or higher price.”USPS original Automation prices go to mail that is presorted, prebarcoded and readable by automated equipment.24Publication 32: Glossary of Postal TermsPDF page 26“A price category for mail that is presorted and prebarcoded and that meets addressing, readability, and other requirements for mail that can be processed on automated equipment.”USPS original They are generally lower than single-piece and nonautomation presorted prices.24Publication 32: Glossary of Postal TermsPDF page 26“Automation prices are generally lower than prices for single-piece mail or nonautomation presorted mail.”USPS original

The OCR read area is a band near the bottom of the address side.25Publication 32: Glossary of Postal Termspage 149“A rectangular area on the address side of the mailpiece that is 1/2 inch from the left and right edges of the mailpiece, 5/8 inch from the bottom edge, and 2-3/4 inches from the bottom edge.”USPS original A letter keeps its lower right corner, the barcode clear zone, free for the barcode.26Publication 32: Glossary of Postal Termspage 23“A rectangular area in the lower right part of a letter-size mailpiece that must be kept free of printing and symbols, except for the barcode itself.”USPS original Its Intelligent Mail barcode goes in the address block or that clear zone.27Intelligent Mail® Barcode FAQPDF page 2“On letters, it can be placed either in the address block or in the barcode clear zone found on the lower right corner of the envelope.”USPS original A package's shipping label goes fully on its address side.28Parcel Labeling Guidepage 48“Always place the label fully on the address side of the package without overlapping the side or any other label.”USPS original

Alternative Designs lets non-rectangular TED-C letters mail at automation letter prices.19PostalPro: Alternative Designs“The USPS and the mailing industry have worked together to create requirements that will allow for the mailing of non-rectangular TED-C letter-size pieces at the automation letter prices.”USPS original Polywrap and Polywrap Manufacturers lists the polywrap approved for automation-rate flats.29PostalPro: Polywrap and Polywrap Manufacturers“The Polywrap Manufacturers link is a downloadable document which lists polywrap manufacturers and distributors of polywrap approved for use on automation rate flat-size mailpieces in compliance with DMM standards effective February 1, 2007.”USPS original Mailpiece Design Analysts, USPS employees trained in mailpiece design, answer questions about a design.30Mailer's Technical Advisory Committee - Best Practices for ACS™page 44“Postal employees specially trained to answer your questions regarding mail piece design.”USPS original

Letter-size mail is the letters and cards that meet the minimum size standards and stay within its maximum dimensions.2Publication 32: Glossary of Postal TermsPDF page 118“A mail processing category that consists of letters and cards meeting minimum size standards and not exceeding the maximum letter-size mail dimensions of 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.”USPS original Its length is the side parallel to the address.9Publication 32: Glossary of Postal TermsPDF page 22“The dimension of a mailpiece expressed as a ratio of length (the direction parallel to the address) divided by height.”USPS original A flat's length is its longest side, wherever the address is.31Full-Service Certification Standardspage 58“The length of a flat is the longest dimension regardless of the address placement”USPS original

A letter more than 6 inches long or 4-1/4 inches high must be at least 0.009 inch thick.6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“For pieces more than 6 inches long or 4-1/4 inches high, the minimum thickness is 0.009.”USPS original A single-piece First-Class Mail letter thinner than that pays the nonmachinable surcharge.6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Pieces not meeting the 0.009 thickness are subject to a nonmachinable surcharge under”USPS original7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original A First-Class Mail letter over 3.5 ounces pays flat prices.6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Not more than 3.5 ounces (First-Class Mail letter-size pieces over 3.5 ounces pay flat-size prices).”USPS original

A card is a letter-size piece of cardstock without an envelope, and also the First-Class Mail price for one.32Publication 32: Glossary of Postal TermsPDF page 36“A letter-size mailpiece of cardstock without an envelope, defined by its dimensions and physical construction. … A unique First-Class Mail price for such a mailpiece.”USPS original A postcard pays card or letter postage, depending on its dimensions.16Publication 32: Glossary of Postal Termspage 173“A commercially produced and sold rectangular card designed for writing and mailing without an envelope and requiring First-Class Mail card or letter postage, depending on the dimensions.”USPS original

A flat must be rectangular, with square corners or corners rounded to a radius of no more than 1/8 inch.3Publication 32: Glossary of Postal TermsPDF page 92“Flat-size mail must be rectangular with four square corners or with finished corners that do not exceed a radius of 1/8 inch.”USPS original It must also be flexible.3Publication 32: Glossary of Postal TermsPDF page 92“Flat-size mail must also be flexible.”USPS original It may be unwrapped, sleeved, wrapped or in an envelope.3Publication 32: Glossary of Postal TermsPDF page 92“Flat-size mail may be unwrapped, sleeved, wrapped, or enveloped.”USPS original Flats claimed at automation prices have different minimum dimensions.3Publication 32: Glossary of Postal TermsPDF page 92“Minimum dimensions are different for flat-size mail claimed at automation prices.”USPS original

A machinable parcel is the size, shape and weight to be sorted safely by machines such as a parcel sorting machine.23Publication 32: Glossary of Postal TermsPDF page 124“A mailpiece that is of the correct size, shape, and weight to be safely sorted by mail processing machinery such as a parcel sorting machine.”USPS original A parcel that isn't machinable is nonstandard, such as one more than 22 inches long, 18 inches wide or 15 inches high.20DMM 201: Commercial Mail, Physical Standards“USPS categorizes parcels into one of two mail-processing categories: machinable or nonstandard. … Dimensions: A parcel that measures more than 22 inches long, or 18 inches wide, or 15 inches high.”USPS original A parcel over 25 pounds is nonstandard too, as is a USPS Marketing Mail parcel under 3.5 ounces.20DMM 201: Commercial Mail, Physical Standards“Weight: A USPS Marketing Mail parcel that weighs less than 3.5 ounces or any parcel that weighs more than 25 pounds.”USPS original Cylindrical tubes and rolls, cans, and wood or metal boxes are nonstandard parcels too.20DMM 201: Commercial Mail, Physical Standards“A parcel is considered nonstandard if it has the following characteristics: … Cylindrical tubes or rolls. … A can, or wood or metal box.”USPS original

USPS called the nonstandard parcel the outside parcel until a DMM revision published January 17, 2016 renamed it the nonmachinable parcel.22Postal Bulletin 22431: DMM Revision: Parcel Simplification (Dec 2015)“As a result, the Postal Service is taking the first step in this initiative by clarifying that the term “outside parcel” is a “nonmachinable parcel” in various sections of the DMM for consistency. … Although this revision will not be published in the DMM until January 17, 2016, these standards are effective immediately.”USPS original The nonmachinable parcel later became the nonstandard parcel.21Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 15“Updated processing categories – retired processing category Irregular (4) and changed Nonmachinable (5) to Nonstandard”USPS original The irregular parcel, one that missed a machinable parcel's dimensions or minimum weight, is a retired category.33Publication 32: Glossary of Postal Termspage 109“A mail processing category for a nonmachinable parcel that does not meet the dimensions or minimum weight of a machinable parcel.”USPS original21Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 15“Updated processing categories – retired processing category Irregular (4) and changed Nonmachinable (5) to Nonstandard”USPS original

Packages of four products pay nonstandard fees past set lengths or volumes:34Publication 205 Electronic Verification System (eVS®) Business and Technical Guidepage 185“Nonstandard fees and requirement for dimensional data disclosure applies to Priority Mail Express, Priority Mail, Parcel Select, and USPS Ground Advantage packages under the following conditions:”USPS original

• Priority Mail Express
• Priority Mail
• Parcel Select
• USPS Ground Advantage

A machinable piece can be sorted by USPS's equipment because its size, shape, configuration and weight fit the equipment's tolerances.23Publication 32: Glossary of Postal TermsPDF page 124“The physical capacity of a mailpiece to be sorted by mail processing equipment because its size, shape, configuration, and weight are within the specifications and tolerances of the equipment.”USPS original A nonmachinable piece can't be, because of its size, shape, content or address legibility.4Publication 32: Glossary of Postal Termspage 146“The incapacity of a mailpiece to be sorted on mail processing equipment because of size, shape, content, or address legibility.”USPS original It is processed by hand and may pay a surcharge or a higher price.4Publication 32: Glossary of Postal Termspage 146“Such mail must be processed manually and may be subject to a surcharge or higher price.”USPS original

An outside is a parcel or piece that must be handled by hand because of its size, weight, shape or contents.35Publication 32: Glossary of Postal Termspage 155“A parcel or mailpiece that, because of size, weight, shape, or contents, must be handled manually.”USPS original It is called an outside because it can't go in a sack or container.35Publication 32: Glossary of Postal Termspage 155“The mailpiece is called an outside because it cannot be placed into a sack or container.”USPS original The outside parcel was something else: a mail processing category, and the old name of the nonstandard parcel.35Publication 32: Glossary of Postal Termspage 155“A mail processing category for a mailpiece that exceeds the dimensions for machinable parcel or a high density item (other than a book or printed matter).”USPS original22Postal Bulletin 22431: DMM Revision: Parcel Simplification (Dec 2015)“As a result, the Postal Service is taking the first step in this initiative by clarifying that the term “outside parcel” is a “nonmachinable parcel” in various sections of the DMM for consistency.”USPS original21Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 15“Updated processing categories – retired processing category Irregular (4) and changed Nonmachinable (5) to Nonstandard”USPS original

A nonmachinable single-piece First-Class Mail letter, stamped or metered, pays the nonmachinable surcharge, $0.49 a piece as of October 4, 2026.12Notice 123: Price List (effective October 4, 2026)“Letters that meet one or more of the nonmachinable characteristics in DMM 101.1.2 are subject to the $0.49 nonmachinable surcharge. … Notice 123 • Effective October 04, 2026”USPS original7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … There are separate prices for stamped letters and for letters with metered postage affixed (Metered Mail price).”USPS original Pieces mailed at the card price don't pay it.7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“Pieces mailed at the card price are not subject to the nonmachinable surcharge.”USPS original It applies to a letter-size piece with one or more of these nonmachinable traits:7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“A letter-size piece is nonmachinable if it has one or more of the following characteristics”USPS original

• An aspect ratio, length divided by height, under 1.3 or over 2.56DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Has an aspect ratio (length divided by height) of less than 1.3 or more than 2.5.”USPS original
• A polybag, polywrap or other plastic cover, or an outside surface that isn't paper6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Is polybagged, polywrapped, enclosed in any plastic material, or has an exterior surface made of a material that is not paper.”USPS original
• Clasps, strings, buttons or similar closures6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Has clasps, strings, buttons, or similar closure devices.”USPS original
• Contents such as pens, keys or coins that make its thickness uneven, or loose objects6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Contains items such as pens, pencils, keys, or coins that cause the thickness of the mailpiece to be uneven; or loose keys or coins or similar objects not affixed to the contents within the mailpiece.”USPS original
• Too rigid to bend easily around an 11-inch turn under 40 pounds of belt tension6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Is too rigid (does not bend easily when subjected to a transport belt tension of 40 pounds around an 11-inch diameter turn).”USPS original
• Less than 0.009 inch thick when more than 6 inches long or 4-1/4 inches high6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Is less than 0.009 inches thick if the mailpiece is more than 6 inches long or 4-1/4 inches high.”USPS original
• A delivery address parallel to its shorter side6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Has a delivery address parallel to the shorter dimension of the mailpiece.”USPS original
• A self-mailer or booklet not prepared to USPS's standards for them6DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels“Is a self-mailer that is not prepared according to … Is a booklet that is not prepared according to”USPS original

A presorted First-Class Mail letter that is nonmachinable pays a nonautomation nonmachinable price instead, one price per presort level.36DMM 233: Commercial First-Class Mail, Prices and Eligibility“Commercial First-Class Mail Presorted cards and letters are charged as follows: … Nonautomation Nonmachinable: One price per presort level up to the maximum 3.5 ounces.”USPS original

The aspect ratio is length divided by height: a postcard 5-1/2 inches long and 3-1/2 inches high has a ratio of 1.57.9Publication 32: Glossary of Postal TermsPDF page 22“The dimension of a mailpiece expressed as a ratio of length (the direction parallel to the address) divided by height. … For example, a postcard 5-1/2 inches long by 3-1/2 inches high has an aspect ratio of 1.57.”USPS original Automation compatibility takes a ratio between 1.3 and 2.5, inclusive.9Publication 32: Glossary of Postal TermsPDF page 22“An aspect ratio between 1.3 and 2.5, inclusive, is required for automation compatibility.”USPS original

Until January 2012, Not Flat-Machinable was a separate price category for Standard Mail pieces of flat size or larger that missed the flats' uniformity or flexibility requirements.25Publication 32: Glossary of Postal Termspage 149“A separate price category for Standard Mail pieces that either meet the size limits for flatsize mail or exceed the length and height for flatsize mail while not meeting the uniformity or flexibility requirements for flat-size mail.”USPS original37Postal Bulletin 22327: DMM revision, new standards for domestic mailing services, Not Flat-Machinables ended (Dec 2011)“We now end the NFM category as of January 2012.”USPS original Standard Mail was renamed USPS Marketing Mail on January 22, 2017.38Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guidepage 3“On January 22, 2017, Standard Mail® underwent a name change and was rebranded as USPS Marketing Mail™”USPS original

The OCR read area is a rectangle on the address side.25Publication 32: Glossary of Postal Termspage 149“A rectangular area on the address side of the mailpiece that is 1/2 inch from the left and right edges of the mailpiece, 5/8 inch from the bottom edge, and 2-3/4 inches from the bottom edge.”USPS original It sits 1/2 inch in from the left and right edges, from 5/8 inch to 2-3/4 inches up from the bottom edge.25Publication 32: Glossary of Postal Termspage 149“A rectangular area on the address side of the mailpiece that is 1/2 inch from the left and right edges of the mailpiece, 5/8 inch from the bottom edge, and 2-3/4 inches from the bottom edge.”USPS original On letter mail, the delivery address usually sits in the lower right.39Publication 32: Glossary of Postal Termspage 58“On letter mail, the delivery address is usually placed in the lower right.”USPS original

A piece that requests ancillary services needs a domestic return address.40OneCode ACS® Technical Guide page 10“A domestic return address is required when ancillary services are requested.”USPS original

The barcode clear zone is a rectangle in the lower right of a letter, kept free of printing and symbols except the barcode.26Publication 32: Glossary of Postal Termspage 23“A rectangular area in the lower right part of a letter-size mailpiece that must be kept free of printing and symbols, except for the barcode itself.”USPS original It lets machines read a barcode there or print one.26Publication 32: Glossary of Postal Termspage 23“This requirement allows automated processing machines to read or apply a barcode.”USPS original A barcode printed in it has its leftmost bar 3-1/2 to 4-1/4 inches from the right edge.41Full-Service Certification Standardspage 60“Horizontally, the leftmost bar must be between 3-1/2 inches and 4-1/4 inches from the right edge of the piece”USPS original It sits between 3/16 inch and 1/2 inch from the bottom edge.41Full-Service Certification Standardspage 60“Vertically, the barcode must be within the area between 3/16 inch and 1/2 inch, both measured from the bottom edge of the piece”USPS original A window envelope has one or two openings on the address side, through which the address or barcode on the insert shows.42Publication 32: Glossary of Postal Termspage 234“An envelope with one or two openings (cutouts) on the address side through which a delivery address or barcode printed on the letter or insert placed in the envelope can be read.”USPS original

On a flat, the Intelligent Mail barcode can go anywhere on the address side at least 1/8 inch from every edge.27Intelligent Mail® Barcode FAQPDF page 2“On flats, the Intelligent Mail barcode can be placed anywhere on the address side as long as it is at least 1/8th inch from any edge of the piece.”USPS original A First-Class Mail flat's delivery address can also go anywhere at least 1/8 inch from the edges, in the same read direction as the postage.31Full-Service Certification Standardspage 58“The delivery address can be placed anywhere on the mailpiece at least 1/8 inch from any edge and it must be printed in the same read direction as the postage”USPS original

On a package, the label goes fully on the address side, without wrapping over an edge or another label.28Parcel Labeling Guidepage 48“Always place the label fully on the address side of the package without overlapping the side or any other label.”USPS original On an unmarked box, the largest side should be treated as the address side.28Parcel Labeling Guidepage 48“When unmarked, the largest side of the box should be considered the address side.”USPS original

USPS and the mailing industry wrote the TED-C requirements, Alternative Designs, so that non-rectangular letters can mail at automation letter prices.19PostalPro: Alternative Designs“The USPS and the mailing industry have worked together to create requirements that will allow for the mailing of non-rectangular TED-C letter-size pieces at the automation letter prices.”USPS original A TED-C letter's die-cut extends past its conventional trailing edge, a line from the upper left corner to the lower left corner.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“TED-C mailpieces are letter-size pieces that have a die-cut that extends past the conventional trailing edge of the mailpiece.”USPS original18Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter PricesPDF page 1“The conventional trailing edge is defined by a line drawn from the upper left corner to the lower left corner.”USPS original Only Full-Service First-Class Mail and USPS Marketing Mail letters with an Intelligent Mail barcode in the address block qualify.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Only Full-Service First-Class Mail letters and USPS Marketing … Mail® letters with an address block Intelligent Mail® barcode (IMb) that meet the TED-C physical standards are eligible for automation prices.”USPS original

A TED-C letter's maximum length, 10.5 inches, and maximum weight, 2.5 ounces, differ from the regular automation letter standards.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Note that the maximum length (10.5”) and maximum piece weight (2.5 oz.) for TED-C mailpieces are modified from regular automation letter standards.”USPS original Its die-cut extends no more than 5/8 inch from the conventional trailing edge.45TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 2“The die-cut cannot extend more than 5/8” from the conventional trailing (left) edge.”USPS original It must meet the minimum length without counting the die-cut.18Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter PricesPDF page 1“When measuring for minimum length and minimum aspect ratio, you cannot include the die-cut design.”USPS original Its maximum length and maximum aspect ratio are measured with the die-cut, so a piece the die-cut makes longer than 10.5 inches pays the nonmachinable letter price.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Note that the maximum length (10.5”) and maximum piece weight (2.5 oz.) for TED-C mailpieces are modified from regular automation letter standards.”USPS original18Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter PricesPDF page 1“When measuring for maximum length and maximum aspect ratio, the die-cut design must be included. (i.e., if the piece is 10 1/8” without the die-cut and the die-cut design makes the piece exceed the 10 ½” maximum, the piece is not eligible for automation letter prices and must be paid at the applicable nonmachinable letter price (See Price List – Notice 123)).”USPS original Mailers may check a piece on the printed TED-C Letters Template, whose four zones stand for the sensors on USPS letter-sorting machines.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Mailers may use the TED-C Letters Template, available on PostalPro at: https://postalpro.usps.com/alternative_designs/ted_c_template, to determine if their mailpiece meets USPS requirements for TED-C mailability.”USPS original45TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 2“The four zones represent the sensors on the machines, or where the lights are placed.”USPS original

To use the template, a mailer places the piece's lower-left corner on it with the bottom edge on the line, then its upper-left corner with the top edge on the line, checking the die-cut at each.45TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 2“1. Place the lower-left corner of the mailpiece on the template and align the bottom edge with the line. … 2. Place the upper-left corner of the mailpiece and align the top edge with the line.”USPS original Some part of the die-cut must reach Zone B or Zone C.45TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 2“Ensure that some part of the die-cut extension extends into Zones B or C.”USPS original A die-cut may show in Informed Delivery's emails, but only one whose leftmost edge is in Zone C is sure to.45TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 2“Yes, the die-cut may be visible in emails provided to Informed Delivery® recipients. … However, to ensure die-cut visibility, the leftmost edge of the die-cut extension must be in Zone C of the TED-C Letter Template.”USPS original A piece whose die-cut's leftmost edge is elsewhere may still mail, with no die-cut showing in Informed Delivery.45TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 2“If the die-cut extension's leftmost edge is not in ZONE C, it may be acceptable to mail, but there may not be any visibility of the die-cut in Informed Delivery® for recipients.”USPS original

Polywrap is clear polythene film used to enclose mailpieces, including automation flat-size pieces.46Publication 32: Glossary of Postal Termspage 165“(1) Clear polythene film used to enclose mailpieces including automation flat-size pieces.”USPS original It is one kind of mailing wrapper, the cover that encloses a piece, with envelopes, sleeves and partial wrappers.47Publication 32: Glossary of Postal Termspage 125“An envelope, sleeve, partial wrapper, or polywrap used to enclose a mailpiece.”USPS original

From March 4, 2007, mailers who polywrapped these pieces had to use polywrap from USPS's approved list:29PostalPro: Polywrap and Polywrap Manufacturers“Mailers may use polywrap in this list immediately, but are required to use approved polywrap from this list as of March 4, 2007 when using polywrap on automation rate flat-size First-Class Mail, Periodicals, and Standard Mail, and on barcoded Bound Printed Matter mailpieces.”USPS original

• Automation-rate First-Class Mail flats
• Automation-rate Periodicals flats
• Automation-rate USPS Marketing Mail flats, then called Standard Mail38Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guidepage 3“On January 22, 2017, Standard Mail® underwent a name change and was rebranded as USPS Marketing Mail™”USPS original
• Barcoded Bound Printed Matter

Any flat-size piece in polywrap must use polywrap from the list, unless it is mailed at saturation, high-density plus or high-density prices.20DMM 201: Commercial Mail, Physical Standards“Polywrap film, or similar coverings on flat-size mailpieces, except for pieces mailed at saturation, high-density plus, or high-density prices, must meet the standards in 4.5. … Only polywrap listed as approved on PostalPro at https://postalpro.usps.com may be used on flat-size mailpieces.”USPS original

A film joins the list after an approved laboratory tests it under USPS-T-3204, USPS's specification for testing polywrap film.48Test Procedures for Automatable Polywrap Filmpage 12“Polywrap manufacturers must submit a polywrap formulation to approved laboratories for testing. … The Postal Service will include approved polywrap formulations in the List of Approved Polywrap.”USPS original49Test Procedures for Automatable Polywrap FilmPDF page 2“Requirements identified in the DMM 4.5.1 Polywrap Specifications refer to specific sections for test methods in USPS-T-3204 – Test Procedures for Automatable Polywrap Film.”USPS original50Test Procedures for Automatable Polywrap Filmpage 1“This specification covers the procedures required to test polywrap film used to enclose flat mail pieces for U.S. Postal Service automated sorting operations.”USPS original The Polywrap Manufacturer List names the manufacturers and distributors of approved polywrap.29PostalPro: Polywrap and Polywrap Manufacturers“The Polywrap Manufacturers link is a downloadable document which lists polywrap manufacturers and distributors of polywrap approved for use on automation rate flat-size mailpieces in compliance with DMM standards effective February 1, 2007.”USPS original

Mailpiece Design Analysts are USPS employees trained to answer questions about mailpiece design.30Mailer's Technical Advisory Committee - Best Practices for ACS™page 44“Postal employees specially trained to answer your questions regarding mail piece design.”USPS original They give advice and issue rulings on whether a piece qualifies for automated rates.30Mailer's Technical Advisory Committee - Best Practices for ACS™page 44“These employees provide advice and issue rulings regarding acceptability for automated rates.”USPS original They help the businesses that design and make mailpieces, such as envelope manufacturers and printers.30Mailer's Technical Advisory Committee - Best Practices for ACS™page 44“MDAs provide technical assistance on mail piece design to envelope manufacturers, printers, advertising agencies, and graphic designers.”USPS original

The Mailpiece Size Checker, at the top right of the EDDM Online Tool, checks a piece against the USPS Marketing Mail flats size requirements.51How to Create an EDDM Bulk MailingPDF page 2“Use the Mailpiece Size Checker, located at the top right of the EDDM Online Tool, to make sure your mailpiece meets the USPS Marketing Mail® Flats size requirements.”USPS original Mailers may check a TED-C letter with the TED-C Letters Template.17TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked QuestionsPDF page 1“Mailers may use the TED-C Letters Template, available on PostalPro at: https://postalpro.usps.com/alternative_designs/ted_c_template, to determine if their mailpiece meets USPS requirements for TED-C mailability.”USPS original A national customer ruling is a USPS decision on a proposed mailing's design and price eligibility, before it reaches a business mail entry unit.52Publication 32: Glossary of Postal TermsPDF page 144“A voluntary customer program administered by USPS that renders decisions on mailpiece design and price eligibility and issues a classification decision on the pieces in the mailer’s proposed mailing before it is presented at a business mail entry unit.”USPS original

• A single-piece First-Class Mail letter with a nonmachinable trait pays the nonmachinable surcharge.7DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility“First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in”USPS original
• A shortpaid nonmachinable First-Class Mail letter goes back to the sender for more postage.14DMM 604: Postage Payment Methods and Refunds“Shortpaid nonmachinable First-Class Mail letters are returned to the sender for additional postage.”USPS original
• A mailing of TED-C pieces that miss the requirements pays nonmachinable letter prices.53Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter PricesPDF page 3“Pieces not meeting the TED-C requirements that are presented as a mailing will be charged nonmachinable letter prices.”USPS original
• A TED-C piece that reaches the 5-inch minimum length only with its die-cut is nonmailable.18Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter PricesPDF page 1“For example, if the piece is 4 ½” in length without the die-cut, and with the die-cut design allows the piece to meet the 5” minimum length, the piece is non-mailable”USPS original
• Polywrap film that fails any of the film tests is unacceptable for USPS automated processing.50Test Procedures for Automatable Polywrap Filmpage 1“Materials that do not meet all of the requirements here are unacceptable for Postal Service automated processing.”USPS original
• A letter envelope whose window intrudes into the barcode clear zone is not eligible for NCOALink MPE.54Guide to Move Updatepage 54“A letter envelope containing a window that intrudes into the barcode clear zone is not eligible for MPE.”USPS original
• Improperly applied package labels can cause scanning problems and affect USPS tracking data.28Parcel Labeling Guidepage 48“Improperly applied shipping labels can cause scanning problems and affect the quality of tracking data provided by USPS.”USPS original