USPS adds a $0.49 nonmachinable surcharge to any letter that its sorting equipment cannot handle, on top of the $0.82 stamped letter price. Square envelopes, clasps, rigid stiffeners, loose keys or coins and an address written the wrong way round are the triggers people meet in practice.
Sixty percent more than a rectangle carrying the same card, on the July 2026 prices.
Paraphrased from USPS Domestic Mail Manual 101.1.2, per pe.usps.com, checked 2026-07-28. Notice 123 states that letters meeting one or more of these characteristics are subject to the $0.49 nonmachinable surcharge.
| Item | Price |
|---|---|
| First-Class Mail letter, stamped, 1 oz | $0.82 |
| First-Class Mail letter, metered, 1 oz | $0.78 |
| Nonmachinable surcharge on a letter | $0.49 |
| First-Class Mail large envelope, 1 oz | $1.69 |
| Parcel characteristics fee, Ground Advantage and Priority | $4.50 |
USPS Notice 123, prices effective July 12, 2026, per pe.usps.com, checked 2026-07-28.
Read the first three rows together. A stamped letter is $0.82 and the surcharge is $0.49, so a square invitation envelope costs about sixty percent more than a rectangular one carrying the same card. The rule sounds arbitrary until you picture the sorting belt: a square piece has no reliable long edge, so a machine cannot orient it, and a person has to.
The two triggers ordinary senders meet are the aspect ratio and the uneven thickness clause. Wedding and party invitations are square by convention. Anything with a key, a coin, a pin or a small charm inside stops being flat. Both push a letter out of the automated stream and into the surcharge.
The manual defines too rigid as not bending easily under 40 pounds of belt tension around an 11 inch turn. A stiffened photo mailer or a chipboard-backed envelope will meet that description even though it looks like ordinary mail. If the piece cannot curve, it is not a machinable letter.
Once contents are thick, rigid or heavy, the piece is a parcel and the letter surcharge stops being relevant. Parcels pick up their own $4.50 characteristics fee for cylindrical tubes and rolls, cans, wooden or metal boxes, and larger volumes of liquid. Different rule, different number.
If your item is rigid or lumpy, the practical move is to stop fighting the letter rules and price it as a small parcel. Here is what four ordinary small items quoted from Newark, NJ 07102 to Atlanta, GA 30303 on 2026-07-28, tracking included.
| Item | Cheapest service | Price |
|---|---|---|
| Ceramic mug in a 6 x 5 x 5 in box, 2 lb | USPS Ground Advantage | $8.48 |
| Smartphone in a 9 x 6 x 1.5 in padded envelope, 0.6 lb | USPS Ground Advantage | $8.86 |
| Cotton t-shirt in a 12 x 9 x 1 in poly mailer, 0.7 lb | USPS Ground Advantage | $8.86 |
| Paperback in an 8 x 5 x 1.5 in box, 1 lb | USPS Ground Advantage | $9.91 |
A parcel label buys tracking and a defined service, which a surcharged letter does not. For anything you would be sorry to lose, that trade is easy. Bear in mind we sell US domestic labels; the letter rules above are Postal Service mail rules and we quote parcels, not stamped mail.
It is $0.49 per letter under USPS Notice 123, prices effective July 12, 2026. It sits on top of the ordinary letter price, which is $0.82 stamped or $0.78 metered for the first ounce.
The manual sets a machinable aspect ratio, length divided by height, of between 1.3 and 2.5. A square piece has a ratio of 1.0, so sorting equipment cannot reliably orient it and a person has to handle it instead.
Not that one. Parcels have their own $4.50 characteristics fee, which USPS applies to cylindrical tubes or rolls, cans, wooden or metal boxes, and parcels holding more than 24 ounces of liquid in glass or a gallon or more in metal or plastic.
As a parcel, in most cases. Four ordinary small items quoted between $8.48 and $9.91 from Newark to Atlanta on 2026-07-28 with tracking included, which no surcharged letter gives you.