The difference between a First-Class stamp and a Forever stamp is smaller than it sounds: a Forever stamp is a First-Class stamp. The meaningful comparison is between the two kinds of First-Class stamps you might have in a drawer. Forever stamps carry no printed value and always cover a one-ounce First-Class letter at whatever the current rate is. Denominated First-Class stamps show a fixed cent amount on the face and stay locked at that value no matter how postage rates change.
What a Forever Stamp Is
The Postal Service introduced the Forever stamp on April 12, 2007 as a nondenominated, nonexpiring stamp that always pays for the first ounce of First-Class Mail.1United States Postal Service. Stamps and Postcards Look at one and you won’t see a price. The stamp’s value floats with the current one-ounce letter rate, which sits at $0.78 as of early 2026.2USPS. Postage Rates and Prices
Because there’s no number on the face, a Forever stamp bought years ago at a lower price still mails a letter today. One purchased in 2020 for $0.55 works fine at the $0.78 rate without any additional postage. That’s the whole appeal.
How Denominated First-Class Stamps Differ
Denominated stamps are the traditional kind, with a specific cent value printed on them. A 55-cent stamp is worth exactly $0.55 of postage, forever. That was enough to mail a one-ounce letter when the rate was $0.55. It falls $0.23 short of today’s $0.78.
Old denominated stamps aren’t worthless. The Postal Service lets you combine any mix of stamp denominations to reach the postage you need.3USPS. Postage Stamps – The Basics You can put a 55-cent stamp on the envelope alongside enough smaller-value stamps to hit $0.78. It works. It’s just tedious, and every rate increase makes the arithmetic worse. Forever stamps sidestep the whole problem.
When the Difference Matters
Rate changes are the moment the two kinds of stamp part ways. The July 2025 rates are the ones currently in force, and USPS has confirmed no mailing price increase for January 2026.4United States Postal Service. Notice 123 – Price List The Postal Service has proposed raising the Forever stamp to $0.82 beginning in July 2026.5United States Postal Service. U.S. Postal Service Recommends New Prices for July If that proposal takes effect, every Forever stamp already sitting in a drawer at $0.78 or less quietly gains value. Every denominated stamp keeps the number on its face and needs makeup postage to mail a letter.
The practical takeaway: buying Forever stamps ahead of a proposed increase costs the same today and saves money later. Buying denominated stamps does the opposite.
What One Forever Stamp Covers
A single Forever stamp mails a standard letter up to one ounce. Weight isn’t the only qualification, though. The envelope also has to meet the physical standards in the Domestic Mail Manual:
- Rectangular with parallel opposite sides
- Height between 3.5 and 6.125 inches
- Length between 5 and 11.5 inches
- Thickness no more than 0.25 inches
Letters can weigh up to 3.5 ounces before USPS reclassifies them as flats.6United States Postal Service. Domestic Mail Manual 101 – Physical Standards for Letters, Cards, Flats, and Parcels Above 3.5 ounces, a letter-sized piece moves into the large envelope category starting at $1.63.4United States Postal Service. Notice 123 – Price List
Postcards have tighter limits: no more than 4.25 by 6 inches and 0.016 inches thick. Stay inside those and the postcard rate is $0.61.4United States Postal Service. Notice 123 – Price List Any dimension over the limit bumps it to the letter rate.
The Nonmachinable Surcharge
Even a one-ounce envelope that fits the size rules can cost more than one Forever stamp. Certain physical features trigger a $0.49 nonmachinable surcharge because USPS sorting equipment can’t process them. Your letter is nonmachinable if it has any of the following:7United States Postal Service. 201 Quick Service Guide
- A square shape (aspect ratio outside 1.3 to 2.5)
- Clasps, strings, or buttons
- Rigid contents like keys or pens
- Uneven thickness
- A nonpaper surface such as fabric or foil
- An address running parallel to the short side of the envelope
Square greeting cards are the classic case. A square invitation costs $0.78 plus $0.49, for $1.27 total. Mail it with a single Forever stamp and the recipient gets hit with postage due.
Adding Postage for Heavier Letters
Each ounce past the first adds $0.29.4United States Postal Service. Notice 123 – Price List USPS sells dedicated additional-ounce stamps at that price, sized to pair with a Forever stamp on the same envelope.8USPS.com. Additional Ounces – Stamps Any mix of stamps totaling the right amount works too.
The tiers for a standard letter:
- 1 ounce: $0.78
- 2 ounces: $1.07
- 3 ounces: $1.36
- 3.5 ounces: $1.36 (partial ounces round up)
Three or four sheets of paper in a standard envelope usually land right around an ounce. Add a stiff card or an extra insert and it tips over. A cheap kitchen scale pays for itself if you mail anything thicker than a short letter.
Global Forever Stamps for International Mail
One boundary worth naming: a domestic Forever stamp only covers mail inside the United States. International letters use a separate Global Forever stamp, currently valued at $1.70, which pays for a one-ounce letter to any country where First-Class Mail International service is available.9USPS.com. Global Poinsettia Stamps The Global stamp floats with the international rate the same way a domestic Forever stamp floats with the domestic rate.
You can stack domestic Forever stamps to reach $1.70 in a pinch, but three of them come to $2.34, which overshoots by $0.64. For any regular international mail, the Global stamp is the cheaper piece of paper.