How Much Is an Additional Ounce Stamp? ($0.29 in 2026)
An additional ounce stamp costs $0.29 in 2026
The USPS additional-ounce rate is $0.29, and it did not change in the July 12, 2026 increase. You add one of these stamps alongside a Forever stamp when a letter weighs more than one ounce. A two-ounce letter therefore costs $1.11 in total ($0.82 plus $0.29).
Letter postage by weight
| Letter weight | Postage needed | Total |
|---|---|---|
| 1 oz | 1 Forever | $0.82 |
| 2 oz | 1 Forever + 1 additional ounce | $1.11 |
| 3 oz | 1 Forever + 2 additional ounce | $1.40 |
| 3.5 oz (max for letters) | 1 Forever + 3 additional ounce | $1.69 |
When you actually need one
Most single-sheet letters stay under one ounce, so the additional-ounce stamp is for heavier mail: multi-page documents, wedding invitations with inserts, and anything on thick cardstock. Five sheets of standard paper in a regular envelope is roughly the point where a second ounce starts to apply. If in doubt, weigh it, because underpaid mail comes back.
Why this rate stayed flat
The additional-ounce price has held at $0.29 across several rate changes while the First-Class letter rate has climbed steadily. USPS adjusts each product separately rather than raising everything by the same percentage. You can see that pattern in the current stamp price breakdown.
Leftover additional-ounce stamps are still worth money
These stamps are Forever-style, so they stay valid at whatever the additional-ounce rate becomes. If you bought a batch for one mailing and have extras, they hold resale value. We buy them alongside regular postage when you sell unused stamps, and you can check how much a book of stamps costs for comparison.
Quick answers
How much is an additional ounce stamp? $0.29, unchanged in the July 2026 rate increase.
How much to mail a 2 oz letter? $1.11 total.
Can I use two Forever stamps instead? Yes, but $1.64 of postage on a $1.11 letter wastes $0.53.
What is the heaviest a letter can be? 3.5 ounces. Above that it is priced as a large envelope.