Additional Ounce Stamp vs. Forever Stamp
Understand what an Additional Ounce stamp pays for, how it differs from a one-ounce Forever stamp, and how to calculate postage for heavier domestic letters.
What Is an Additional Ounce Stamp?
An Additional Ounce stamp is designed to add the current additional-ounce amount to a qualifying domestic First-Class Mail letter. It is most commonly used after base postage has already been covered—for example, by one regular Forever stamp.
The words “Additional Ounce” describe a postage category, not a complete one-ounce letter rate. At the rates effective July 12, 2026, the category is worth $0.29. USPS rules state that nondenominated stamps labeled for this category follow the applicable additional-ounce price at the time of use.
This makes the stamp convenient when a standard machinable letter weighs more than one ounce. It does not automatically solve postage for every heavy envelope: shape, rigidity, thickness, dimensions, destination, and requested services can change the required price.
Additional Ounce Stamp vs. Forever Stamp
| Feature | Forever Stamp | Additional Ounce Stamp |
|---|---|---|
| Primary purpose | Pays the base one-ounce stamped-letter rate | Adds the applicable extra-ounce amount |
| Value as of July 12, 2026 | $0.82 | $0.29 |
| Typical use | Base postage for a qualifying domestic letter up to one ounce | Supplemental postage when a qualifying letter exceeds one ounce |
| Enough by itself for a one-ounce letter? | Yes, when the letter meets the standard stamped-letter requirements | No; $0.29 is below the current $0.82 base price |
| Value after a rate change | Tracks the current one-ounce stamped-letter price | Tracks the current additional-ounce category price when labeled for that category |
If you are looking for regular one-ounce postage, see the Discount Forever Stamps guide and available options.
How Much Postage Does a Heavier Letter Need?
For a standard machinable domestic stamped letter, the July 12, 2026 USPS prices increase by $0.29 for each additional ounce or fraction represented in the published weight steps, up to the 3.5-ounce letter maximum. The following combinations assume the envelope qualifies for ordinary letter pricing and needs no surcharge or extra service.
| Letter weight | USPS price | Example stamp combination |
|---|---|---|
| Up to 1 ounce | $0.82 | 1 Forever stamp |
| Over 1 ounce, up to 2 ounces | $1.11 | 1 Forever stamp + 1 Additional Ounce stamp |
| Over 2 ounces, up to 3 ounces | $1.40 | 1 Forever stamp + 2 Additional Ounce stamps |
| Over 3 ounces, up to 3.5 ounces | $1.69 | 1 Forever stamp + 3 Additional Ounce stamps |
Two-ounce example: $0.82 + $0.29 = $1.11
Three-ounce example: $0.82 + $0.29 + $0.29 = $1.40
3.5-ounce example: $0.82 + $0.29 + $0.29 + $0.29 = $1.69
Do not use this table for large envelopes, packages, international mail, or letters subject to a nonmachinable surcharge. Those mailpieces follow other prices or add-on charges.
Real-World Mailing Examples
Standard greeting card: A rectangular, flexible card weighing 0.8 ounces needs one Forever stamp at the current one-ounce stamped-letter price.
Wedding invitation with an RSVP card: If the completed machinable envelope weighs 1.6 ounces, the exact weight-based amount is one Forever stamp plus one Additional Ounce stamp, or $1.11 at the rates effective July 12, 2026.
Letter with printed photographs: If a qualifying 6-by-9-inch envelope remains flexible, uniformly thick, and weighs 2.4 ounces, the weight-based amount is one Forever stamp plus two Additional Ounce stamps, or $1.40 at the same rates.
These examples apply only when the finished mailpiece qualifies for ordinary machinable letter pricing. Square, rigid, uneven, oversized, or international mail may require a different price or an additional surcharge.
Can You Use Additional Ounce Stamps by Themselves?
An Additional Ounce stamp is valid postage and counts toward the total affixed amount, but one stamp by itself is not enough for a standard one-ounce letter at current rates. USPS requires the total postage to meet at least the applicable charge.
For example, placing only one $0.29 Additional Ounce stamp on a one-ounce letter leaves the mailpiece $0.53 short of the current $0.82 base rate. The clearer and more convenient combination for a qualifying two-ounce letter is one Forever stamp plus one Additional Ounce stamp.
What if you do not have an Additional Ounce stamp?
You may combine other valid U.S. postage stamps to reach the required total. For a two-ounce letter costing $1.11, one $0.82 Forever stamp plus other stamps totaling $0.29 meets the price. Affixing two one-ounce Forever stamps would provide $1.64, which is enough but overpays by $0.53.
Exact-value combinations reduce waste, but a small overpayment is generally preferable to underpaying. When you are unsure of the mailpiece category or required postage, weigh the completed envelope and use an official USPS calculator or ask at a Post Office.
Common Additional Ounce Stamp Mistakes
- Using one Additional Ounce stamp as the base postage. Its $0.29 value does not cover the current $0.82 one-ounce stamped-letter price.
- Using two Forever stamps when an exact combination is available. Two Forever stamps cover a qualifying two-ounce letter but overpay the current $1.11 price by $0.53.
- Assuming one Forever stamp covers any letter weight. The Forever designation follows the one-ounce stamped-letter price; extra weight still requires additional postage.
- Weighing an empty envelope instead of the finished mailpiece. Insert every card, photograph, reply envelope, and enclosure before checking the final weight and dimensions.
Weight Is Not the Only Factor
Extra weight is only one reason a letter may need more postage. A square, rigid, nonrectangular, or uneven envelope may be nonmachinable and require a separate surcharge. A large envelope (flat) starts with a different base price, so adding one Additional Ounce stamp to a regular Forever stamp may still leave it underpaid.
- Weigh the envelope after inserting all pages, cards, photographs, or reply materials.
- Measure the finished envelope and check whether it remains flexible and uniformly thick.
- Confirm that it is a domestic letter rather than a large envelope, package, or international mailpiece.
- Add any applicable surcharge or extra-service fee separately.
Current Availability on This Site
Additional Ounce stamps are not currently listed as available inventory on this site, so this page is provided as a postage explanation and comparison guide rather than a product sales page. We do not display a purchase button or imply that unavailable stamps can be ordered.
If you need base postage for standard one-ounce letters, you can compare Forever stamp options or browse all currently listed stamps. If Additional Ounce inventory is added later, product information can be included here without changing this guide's URL.
Frequently Asked Questions
What is an Additional Ounce stamp?
An Additional Ounce stamp pays the current First-Class Mail additional-ounce price for a qualifying domestic letter. It supplements the base postage; it is not the same as a one-ounce Forever stamp.
How much is an Additional Ounce stamp worth?
As of July 12, 2026, the First-Class Mail additional-ounce price for a single-piece letter is $0.29. USPS prices can change, so verify the current Notice 123 price list before mailing.
Are Additional Ounce stamps Forever stamps?
USPS treats nondenominated stamps labeled for the additional-ounce category as equal to the current applicable additional-ounce price at the time of use. Their value follows that category, not the one-ounce Forever stamp rate.
Can I use an Additional Ounce stamp by itself?
It counts toward postage, but one $0.29 Additional Ounce stamp by itself does not cover the current $0.82 postage for a standard one-ounce stamped letter. The total postage affixed must meet the applicable price.
How many Additional Ounce stamps do I need for a three-ounce letter?
At the rates effective July 12, 2026, a qualifying three-ounce stamped letter costs $1.40: one $0.82 Forever stamp plus two $0.29 additional-ounce amounts.
Can regular stamps replace an Additional Ounce stamp?
Yes. You may combine valid U.S. postage stamps as long as the total affixed postage meets or exceeds the required amount. An Additional Ounce stamp is convenient, but it is not the only way to add $0.29.
Does an Additional Ounce stamp cover a square or rigid envelope?
Not necessarily. Square, rigid, uneven, or otherwise nonmachinable letters may require a separate surcharge, and large envelopes use a different price table. Check the mailpiece shape and dimensions as well as its weight.
Official Sources and Update Note
Prices on this page were checked against USPS Notice 123 effective July 12, 2026. USPS pricing and mailing standards can change. Verify the current rate and the classification of your finished mailpiece before sending.
- USPS Notice 123: current price list
- USPS DMM 604: postage payment methods and stamp values
