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USPS Size guidelines
Last Updated: 06/16/2016
Physical Standards for Letters
Dimensional Standards for Letters
Letter-size mail is:
a. Min 5 x 3.5 x .007" - For 6 x 4.5" + min is 0.009"
b. Max 11.5 x 6.125 x .25"
c. Max 3.5 ounces
d. Rectangular, with four square corners and parallel opposite sides. Letter-size, card-type mailpieces made of cardstock may have finished corners that do not exceed a radius of 0.125 inch (1/8 inch).
A letter-size piece is nonmachinable if it has one or more of the following characteristics (see 601.1.1.2 to determine the length, height, top, and bottom of a mailpiece):
a. Has an aspect ratio (length divided by height) of less than 1.3 or more than 2.5.
b. Is polybagged, polywrapped, enclosed in any plastic material, or has an exterior surface made of a material that is not paper. Windows in envelopes made of paper do not make mailpieces nonmachinable. Attachments allowable under applicable eligibility standards do not make mailpieces nonmachinable.
c. Has clasps, strings, buttons, or similar closure devices.
d. 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. Loose items may cause a letter to be nonmailable when mailed in paper envelopes; (see 601.3.3).
e. Is too rigid (does not bend easily when subjected to a transport belt tension of 40 pounds around an 11-inch diameter turn).
f. For pieces more than 4-1/4 inches high or 6 inches long, the thickness is less than 0.009 inch.
g. Has a delivery address parallel to the shorter dimension of the mailpiece.
h. Is a self-mailer that is not prepared according to 201.3.14.
i. Is a booklet that is not prepared according to 201.3.16.
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Physical Standards for Flats
General Definition of Flat-Size Mail
Flat-size mail is:
a. More than 11-1/2 inches long, or more than 6-1/8 inches high, or more than 1/4 inch thick, except as allowed for EDDM-Retail flats under 140. For general retail mailability, all pieces 1/4 inch thick or less must be a minimum of 5 inches long and 3-1/2 inches high and 0.007 inch thick.
b. Not more than 15 inches long, or more than 12 inches high, or more than 3/4 inch thick.
c. Flexible (see 2.3).
d. Rectangular with four square corners or with finished corners that do not exceed a radius of 0.125 inch (1/8 inch). See Exhibit 18.104.22.168.
e. Uniformly thick (see 2.4).
f. Unwrapped, sleeved, wrapped, or enveloped.
Length and Height of Flats
The length of a flat-size mailpiece is the longest dimension. The height is the dimension perpendicular to the length.
Minimum Flexibility Criteria for Flat-Size Pieces
Flat-size pieces must be flexible. Boxes—with or without hinges, gaps, or breaks that allow the piece to bend—are not flats. Tight envelopes or wrappers that are filled with one or more boxes are not flats. At the customer's option, a customer may perform the following test on their own mailpieces. When a postal employee observes a customer demonstrating that a flat-size piece is flexible according to these standards, the employee does not need to perform the test. Test flats as defined in 201.4.3.
Flat-size mailpieces must be uniformly thick so that any bumps, protrusions, or other irregularities do not cause more than 1/4-inch variance in thickness. When determining variance in thickness, exclude the outside edges of a mailpiece (1 inch from each edge) when the contents do not extend into those edges. Also, exclude the selvage of any polywrap covering (see 201.5.3 from this determination. Mailers must secure nonpaper contents to prevent shifting of more than 2 inches within the mailpiece if shifting would cause the piece to be nonuniform in thickness or would result in the contents bursting out of the mailpiece (see 601.3.3).
Flat-Size Pieces Not Eligible for Flat-Size Pricing
Flat-size mailpieces that do not meet the standards in 2.1 through 2.4 are not eligible for flat-size pricing and must pay applicable parcel prices.
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Physical Standards for Parcels
[4-10-16] USPS categorizes parcels into one of three mail processing categories: machinable, irregular, or nonmachinable parcel. These categories are based on the physical dimensions of the piece, regardless of the placement (orientation) of the delivery address on the piece.
Maximum Weight and Size
[1-17-16] All parcels must be large enough to hold the required delivery address, return address, mailing labels, postage, barcode, endorsements, and other mail markings on the address side of the parcel. For mailability, all pieces 1/4 inch thick or less must be a minimum of 5 inches in length, 3-1/2 inches in height, and 0.007 inch in thickness. No mailpiece may weigh more than 70 pounds or measure more than 108 inches in length and girth combined, except USPS Retail Ground, which may not measure more than 130 inches in length and girth combined. For parcels, length is the distance of the longest dimension and girth is the distance around the thickest part. Lower size or weight standards apply to mail addressed to some APOs and FPOs subject to 703.2.0 and 703.4.0 and for Department of State mail, subject to 703.3.0. For additional information on machinable, irregular, and nonmachinable parcels see 201.7.0.
Two or More Packages
With the exception of USPS-produced Flat Rate Envelopes and Boxes, two or more packages may be mailed as a single parcel, if they are about the same size or shape, if they are securely wrapped or fastened together, and if they do not together exceed the weight or size limits.
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Additional Physical Standards for Priority Mail Express
Each piece of Priority Mail Express may not weigh more than 70 pounds. The combined length and girth of a piece (the length of its longest side plus the distance around its thickest part) may not exceed 108 inches. Lower size or weight standards apply to Priority Mail Express addressed to certain APO/FPO and DPOs. Priority Mail Express items must be large enough to hold the required mailing labels and indicia on a single optical plane without bending or folding.
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Additional Physical Standards for Priority Mail
The maximum weight is 70 pounds. The combined length and girth of a piece (the length of its longest side plus the distance around its thickest part) may not exceed 108 inches. Lower size and weight standards apply for some APO/FPO and DPO mail subject to 703.2.0, and 703.4.0, and for Department of State mail subject to 703.3.0.
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Additional Physical Standards for First-Class Mail
First-Class Mail cannot exceed 13 ounces. First-Class Mail weighing more than 13 ounces is Priority Mail.
Cards Claimed at Card Prices
6.2.1 Card Price
A card may be a single or double (reply) stamped card or a single or double postcard. Stamped cards are available from USPS with postage imprinted on them. Postcards are commercially available or privately printed mailing cards. To be eligible for card pricing, a card and each half of a double card must meet the physical standards in 6.2 and the applicable eligibility and preparation standards for the price claimed. Ineligible cards are subject to letter-size pricing. Cards may be prepared and mailed at the First-Class Mail single-piece card, Presorted card, or automation card prices.
6.2.2 Postcard Dimensions
Each card and part of a double card claimed at card pricing must be:
b. Not less than 3-1/2 inches high, 5 inches long, and 0.007 inch thick.
c. Not more than 4-1/4 inches high, or more than 6 inches long, or greater than 0.016 inch thick.
6.2.3 Other Cards
A card that does not meet the applicable standards in 6.2 must not bear the words “Postcard” or “Double Postcard.”
6.2.4 Paper or Card Stock
A card must be of uniform thickness and made of unfolded and uncreased paper or cardstock of approximately the quality and weight of a stamped card (i.e., a card available from the USPS). A card must be formed either of one piece of paper or cardstock or of two pieces of paper permanently and uniformly bonded together. The stock used for a card may be of any color or surface that permits the legible printing of the address, postmark, and any required markings.
6.2.5 Acceptable Attachments
A card may bear an attachment that is:
a. A paper label, such as a wafer seal or decal affixed with permanent adhesive to the back side of the card, or within the message area on the address side (see Exhibit 202.2.1), or to the left of the address block.
b. A label affixed with permanent adhesive for showing the delivery or return address.
c. A small reusable seal or decal prepared with pressure-sensitive and nonremovable adhesive that is intended to be removed from the first half of a double card and applied to the reply half.
6.2.6 Unacceptable Attachment
A card may not bear an attachment that is:
a. Other than paper.
b. Not totally adhered to the card surface.
c. An encumbrance to postal processing.
6.2.7 Tearing Guides
A card may have perforations or tearing guides if they do not eliminate or interfere with any address element, postage, marking, or endorsement and do not impair the physical integrity of the card.
6.2.8 Address Side of Cards
The address side of a card is the side bearing the delivery address and postage. The address side may be formatted to contain a message area. Cards that do not contain a message area on the address side are subject to the applicable standards for the price claimed. For the purposes of 6.2, miscellaneous graphics or printing, such as symbols, logos, or characters, that appear on the address side of cards not containing a message area are generally acceptable provided the items are not intended to convey a message.
6.2.9 Double Cards
A double card (a double stamped card or double postcard) consists of two attached cards, one of which is designed to be detached by the recipient and returned by mail as a single card. Double cards are subject to these standards:
a. The reply half of a double card must be used for reply only and may not be used to convey a message to the original addressee or to send statements of account. The reply half may be formatted for response purposes (e.g., contain blocks for completion by the addressee).
b. A double card must be folded before mailing and prepared so that the address on the reply half is on the inside when the double card is originally mailed. The address side of the reply half may be prepared as Business Reply Mail, Courtesy Reply Mail, meter reply mail, or as a merchandise return service label.
c. Plain stickers, seals, or a single wire stitch (staple) may be used to fasten the open edge at the top or bottom once the card is folded if affixed so that the inner surfaces of the cards can be readily examined. Fasteners must be affixed according to the applicable preparation requirements for the price claimed. Any sealing on the left and right sides of the cards, no matter the sealing process used, is not permitted.
d. The first half of a double card must be detached when the reply half is mailed for return.
Enclosures in double postcards are prohibited at card prices.
6.3.1 Nonmachinable Letters
Letter-size pieces (except card-size pieces) that meet one or more of the nonmachinable characteristics in 1.2 are subject to the nonmachinable surcharge (see 133.1.5).
6.3.2 Nonmachinable Flats
Flat-size pieces that do not meet the standards in 2.0 are subject to the applicable postage for a parcel-size piece, based on weight.
First-Class Mail parcels are eligible for USPS Tracking and Signature Confirmation services. A First-Class Mail parcel is:
a. A mailpiece that exceeds any one of the maximum dimensions for a flat (large envelope). See 2.1.
b. A flat-size mailpiece, regardless of thickness, that is rigid or nonrectangular.
c. A flat-size mailpiece that is not uniformly thick under 2.4.
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Additional Physical Standards for USPS Retail Ground
These standards apply to USPS Retail Ground:
a. No piece may weigh more than 70 pounds.
b. USPS Retail Ground pieces measuring over 108 inches in combined length and girth, but not more than 130 inches in combined length and girth, are mailable at the applicable oversized price.
c. USPS Retail Ground pieces measuring over 84 inches in combined length and girth, but not more than 108 inches in combined length and girth, and weighing less than 20 pounds are mailable at the price equal to that of a 20-pound parcel for the zone to which the parcel is addressed (balloon price).
d. Lower size or weight standards apply to mail addressed to some APOs and FPOs subject to 703.2.0 and 703.4.0 and for Department of State mail, subject to 703.3.0.
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Additional Physical Standards for Media Mail and Library Mail
These standards apply to Media Mail and Library Mail:
a. No piece may weigh more than 70 pounds.
b. The combined length and girth of a piece (the length of its longest side plus the distance around its thickest part) may not exceed 108 inches.
c. Lower size or weight standards apply to mail addressed to certain APOs and FPOs, subject to 703.2.0 and 703.4.0 and for Department of State mail, subject to 703.3.0.
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