An additional ounce stamp costs $0.29 in July 2026, which is what each extra ounce adds to a stamped letter after the first. So how much is an additional ounce stamp in practice? A 2 oz letter needs $1.11 in postage, a 3 oz letter needs $1.40, and a 3.5 oz letter needs $1.69.
The first ounce is covered by a regular Forever stamp, now $0.82. Everything above that is billed in ounce steps until the letter hits 3.5 oz. The prices below come from the July 12, 2026 USPS Notice 123 price list.
How much is an additional ounce stamp in 2026?
How much is an additional ounce stamp worth on its own? It is printed with a 29 cent value, the same as the extra charge for one more ounce. You can see the current options on the USPS Postal Store additional ounces page.
USPS also sells Two Ounce stamps at $1.11 and Three Ounce stamps at $1.40. Those two cover the full postage for a letter of that weight, so you do not need a Forever stamp with them.
What is an additional ounce stamp used for?
It tops up a stamp you already have. Put a Forever stamp on a letter that weighs more than 1 oz, then add one Additional Ounce stamp for each extra ounce or part of an ounce. The weight steps round up, so a letter at 1.1 oz is charged as a 2 oz letter.
Mail with a Forever stamp plus the right extras works the same as one stamp of the full value. USPS accepts any mix of stamps that adds up to the correct amount. Our guide to how a Forever stamp works explains why the older stamps keep their value.
How much is an additional ounce stamp by letter weight?
Stamped letter prices rise in $0.29 steps. Metered postage, which businesses print with a postage meter, costs $0.04 less at each step. A stamp is the right choice for most home mail.
| Letter weight (not over) | Stamped price | Stamps you need |
|---|---|---|
| 1 oz | $0.82 | 1 Forever stamp |
| 2 oz | $1.11 | 1 Forever + 1 Additional Ounce |
| 3 oz | $1.40 | 1 Forever + 2 Additional Ounce |
| 3.5 oz | $1.69 | 1 Forever + 3 Additional Ounce |
The metered prices for the same four weights are $0.78, $1.07, $1.36 and $1.65. For a longer list of weights and mail types, see the full First-Class Mail price chart.
How many ounces does a Forever stamp cover?
A Forever stamp is priced to match the 1 oz stamped letter rate, $0.82 right now. The USPS letters page says one $0.82 Forever stamp sends 1 oz anywhere in the United States, and that for letters up to 3.5 oz each additional ounce is $0.29. Anything heavier than 1 oz needs added postage.
A quick way to judge weight is by paper. USPS puts 1 oz at about four sheets of regular 8.5 by 11 inch paper in a rectangular envelope, but it depends on the paper and the envelope. The article on how many sheets one stamp covers goes through that in detail.
How much is a second ounce stamp?
The second ounce adds $0.29. A letter that weighs just over 1 oz moves from $0.82 to $1.11. Use one Forever stamp and one 29 cent Additional Ounce stamp, or one Two Ounce stamp on its own.
The price of an extra ounce stamp stays at $0.29 each time. The third ounce adds another $0.29, which takes the total to $1.40. The half ounce step from 3 oz to 3.5 oz adds $0.29 again, for $1.69.
What happens when a letter weighs more than 3.5 oz?
Letters stop at 3.5 oz, and a letter envelope can be at most 11.5 inches long by 6.125 inches high. Anything heavier or bigger is priced as a large envelope, also called a flat, which USPS prices up to 13 oz. A 1 oz large envelope starts at $1.69, which is the same as a 3.5 oz letter.
Each additional ounce on a large envelope also adds $0.29 at first, but the totals climb fast. The table shows the first few steps.
| Large envelope weight (not over) | Price |
|---|---|
| 1 oz | $1.69 |
| 2 oz | $1.98 |
| 3 oz | $2.27 |
| 4 oz | $2.56 |
| 8 oz | $3.72 |
| 13 oz | $5.24 |
The step changes slightly past 8 oz, so it is no longer an even $0.29 for every ounce. Check the guide on stamps for a large envelope before you buy extra stamps.
When does a letter cost more than the weight price?
Some letters pay a nonmachinable surcharge of $0.49 on top of the weight price. USPS applies it to letters with a shape or feature its machines cannot process well. Its own list names envelopes that are lumpy or rigid, or have clasps, string or buttons, plus square envelopes and vertical ones that are taller than they are wide.
A 1 oz letter in a nonmachinable envelope would then need $0.82 plus $0.49, or $1.31. This surcharge is separate from the ounce steps. If your envelope is stiff or square, ask the counter or run it through the stamp calculator first.
How to build the right postage with stamps
Weigh the filled envelope on a kitchen or postal scale, then round up to the next ounce. Match that weight to the table above and add the stamps in the last column. Seal the envelope first, because the flap and any inserts change the weight.
Say you mail a 2.4 oz letter. It falls in the 3 oz step, so it needs $1.40. Put one Forever stamp at $0.82 and two Additional Ounce stamps at $0.29 each, which comes to exactly $1.40.
Now say you only have Forever stamps. Two of them total $1.64, which covers a letter up to 3 oz at $1.40. You overpay by $0.24, and USPS does not give change, so it is cheaper to buy the extra stamps.
Where to place the extra stamps
Put all the stamps in the upper right corner of the front, in a neat row or stack. Leave room for the postmark and keep the address block clear. Our guide on where to put a stamp on an envelope shows the layout.
Stamps on the back or across the address can slow a letter or cause it to be returned. If the corner looks crowded, a single Two Ounce or Three Ounce stamp is the cleaner choice.
Do postcards need an additional ounce stamp?
No. A postcard costs a flat $0.65, and it has no ounce steps. Oversized or thick postcards are priced as letters, so the ounce rules return.
What if I put too little postage on a letter?
A letter with short postage can be returned to you or delivered with postage due, which the recipient pays. The cost is the missing amount, plus a handling charge in some cases. USPS does not publish a single fee for every case, so the safe habit is to weigh the letter and add the extra stamp.
Round up when you are unsure. One extra 29 cent stamp is a small price next to a delayed or returned letter.
Bottom line on the extra ounce price
Each extra ounce on a letter costs $0.29, and a letter can reach 3.5 oz before it becomes a large envelope. Pair one Forever stamp with the number of Additional Ounce stamps shown in the table, and you will not overpay.
For other weights and envelope types, the guide to how many stamps you need covers them.
Prices for every common stamp are on the current stamp price page.
