Post Offices and the USPS Postal Store provide several kinds of envelopes and mailing supplies, but free service-branded packaging is not prepaid postage and cannot be used with an incompatible service.
Choose the envelope by the mailing task
| Supply | Does it include postage? | When to use it |
|---|---|---|
| Ordinary envelope | No | Letters when its size, shape and strength qualify |
| Stamped envelope | Yes, for the printed postage value or class | Convenient letter stationery; add postage when required |
| Free Priority Mail packaging | No | Only with the corresponding Priority Mail service |
| Your own Ground Advantage packaging | No | Packages prepared under Ground Advantage limits |
| Certified Mail form and label | No by itself | Adds the selected extra service to otherwise fully paid eligible mail |
What “free USPS envelope” means
USPS supplies some Priority Mail and Priority Mail Express packaging without a separate packaging charge because it is service-specific. The sender still pays the applicable postage, and the packaging must not be used with a lower or unrelated service. A free box or envelope is therefore different from a prepaid envelope.
Ground Advantage normally uses suitable customer-provided packaging. Choose a mailer strong enough for the contents and large enough to carry the address, postage and barcode area without folds.
Where to get mailing supplies
- Use the USPS Postal Store for official stamped stationery, service packaging, forms and labels.
- Ask a local Post Office about on-hand supplies; local availability can differ.
- Use a retailer for ordinary envelopes, padded mailers and packing materials.
- Check the exact product name before assuming an envelope includes postage.
If you are mailing a letter, follow the full USPS envelope preparation guide after selecting the envelope.
Size, shape and postage checks
A product called an “envelope” can rate as a letter, large envelope or package depending on its finished dimensions, thickness, rigidity and contents. Assemble and weigh the final mailpiece. Square, rigid, lumpy or unusually thick pieces may require a surcharge or a different category.
Sources and update note
Facts and availability checked September 10, 2026.