Reviewed September 12, 2026. A qualifying one-ounce domestic First-Class Mail letter costs 82 cents. Each additional ounce costs 29 cents, effective July 12, 2026. The correct stamp count depends on the finished mailpiece, not weight alone.
Current machinable letter examples
| Weight | Required postage | Ordinary Forever stamps only |
|---|---|---|
| Up to 1 oz | $0.82 | 1 stamp |
| Over 1 oz to 2 oz | $1.11 | 2 stamps = $1.64, overpay $0.53 |
| Over 2 oz to 3 oz | $1.40 | 2 stamps = $1.64, overpay $0.24 |
Using one ordinary Forever stamp plus appropriate smaller-denomination postage can reduce overpayment.
Shape and machinability can change the result
A square, rigid, nonrectangular or uneven letter may incur a nonmachinable surcharge. A large, rigid or lumpy envelope may be priced as a package. Review the USPS physical standards and current prices.
Calculation order
- Confirm domestic or international destination.
- Measure length, height and thickness.
- Weigh the sealed piece.
- Check flexibility, uniform thickness and rectangular shape.
- Identify the mail class and current total.
- Add stamp values and show any overpayment.
Do not use the 2025 rate for current mail
A 78-cent ordinary Forever value is historical. The examples above use the 82-cent value effective July 12, 2026. Verify the current USPS price before mailing because later rate changes would alter each calculation.
For unusual pieces, verify the result with the USPS postage calculator or at a Post Office.