Will it go as a letter?
Check a card mailer against the USPS letter rules before you stamp it. Size, thickness, weight and stiffness decide the price, and whether the barcode gets scanned at all.
Start from a common setup or type your own numbers.
The rules this checks
From the USPS Domestic Mail Manual, section 101, and the USPS price list effective October 4, 2026.
A letter
At least 5 by 3 1/2 inches and 0.007 inch thick, at most 11 1/2 by 6 1/8 inches, 1/4 inch thick and 3.5 ounces. Bigger, thicker or heavier is a large envelope, if it stays flexible and even.
What makes a letter nonmachinable
Length divided by height under 1.3 or over 2.5 (a square envelope fails); plastic outside; a clasp, string or button; lumpy contents like coins or pens; too stiff to bend around a sorting belt; or the address along the short side. A nonmachinable letter costs $0.49 more and is sorted by hand, which usually means few or no barcode scans.
Stamped prices
| Weight up to | Letter | Large envelope |
|---|---|---|
| 1 oz | $0.82 | $1.69 |
| 2 oz | $1.11 | $1.98 |
| 3 oz | $1.40 | $2.27 |
| 3.5 oz | $1.69 | $2.56 (up to 4 oz) |
Large envelopes go up to 13 oz ($5.24), 15 by 12 inches and 3/4 inch thick. Past that it is a package. A Forever stamp is always worth the 1 oz letter price.
PigeonTrail prints a USPS tracking barcode on letters and large envelopes you stamp yourself, then shows your buyer every scan. Try it free, 100 letters a month.