A postage stamp is evidence that an amount has been prepaid toward delivering a mailpiece.
How postage is calculated
Mail class, weight, dimensions, shape, destination, and optional services determine the required amount. One stamp is not automatically enough for every envelope.
Forever and fixed-value stamps
A domestic Forever Stamp follows the current one-ounce letter rate. A fixed-denomination stamp contributes only the amount printed on it. Valid stamps can be combined.
Why stamps are canceled
Postal processing marks stamps to show they have been used. Reusing a canceled or previously used stamp is not valid postage.
How to use a stamp
Remove the backing if self-adhesive, place the stamp flat in the upper-right corner of the address side, and do not cover it with tape.
Frequently asked questions
What does postage mean?
The amount paid for postal delivery and related services.
Can I combine stamps?
Yes, if they are unused and valid and their total value meets the required postage.
Does every letter need one Forever Stamp?
No. Weight, shape, dimensions, destination, and services can require a different amount.
Sources and update note
- USPS Notice 123 — current price list
- USPS DMM 101 — physical standards
- USPS DMM 604 — postage payment methods
Rates and mailing standards can change. This page was reviewed in August 2026; verify the completed mailpiece when its weight, dimensions, shape, destination, or services are uncertain.
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