Can you mail a package with stamps?
Yes, but a package that uses stamps and is more than 1/2 inch thick or more than 10 oz must be handed to a Post Office counter. Left in your mailbox, the carrier will leave it; dropped in a blue collection box, it comes back to you.
Stamps also pay retail prices: a 4 oz Ground Advantage package to Zone 5 needs $9.35 in stamps (12 Forever stamps at 82¢), against $8.24 with an online label.
Rates verified on
Postage in the examples is from Notice 123 effective Oct 4, 2026, which includes USPS's temporary holiday prices for Ground Advantage and Priority Mail until 12 a.m. CT Jan 17, 2027. The fees quoted here are the same as in the July 12, 2026 edition, before the holiday prices began.
The rule, in USPS's words
“If your package uses stamps and is more than one-half inch thick or weighs more than 10 oz, you must take it to a Post Office counter and give it to the Retail Associate at the counter.”
“if you put it in your mailbox for pickup, the carrier will leave it. If you drop it in a blue collection box or Post Office lobby mail receptacle, it will be returned to you.”
“If you're mailing restricted hazardous materials, you can't use stamps—use one of the other methods to pay for postage.”
“Registered end-users of USPS-approved PC Postage products when using a qualifying shipping label, managed by the PC Postage system.”
“the total postage affixed must equal at least the postage charge for the class of the mail”
What it costs, with examples
| Piece | Postage | Forever stamps | Drop it in a mailbox? | Online label |
|---|---|---|---|---|
| Ground Advantage parcel, 9 oz, 3/8 in. thick, Zone 5 | $11.70 | 15 | yes (under 10 oz and under 1/2 in.) | $8.24 |
| The same parcel in a 3/4 in. thick mailer | $11.70 | 15 | no: counter (over 1/2 in.) | $8.24 |
| Ground Advantage parcel, 4 oz, Zone 5 | $9.35 | 12 | only if under 1/2 in. thick | $8.24 |
| Media Mail book, 1 lb | $4.39 | 6 | no: counter (over 10 oz) | $4.39 (same price) |
Edge cases
- Stamps can't buy commercial prices: the DMM gives them to PC Postage labels, IBI meters and permit imprint (DMM 283.1.2), and USPS says its own Click-N-Ship sells Priority Mail and Ground Advantage at commercial rates too (USPS).
- Overpaying: Forever stamps rarely add up to the exact price; 12 stamps for the 4 oz parcel above is $0.49 more than the postage. Smaller stamps can make up the difference.
- APO/FPO/DPO: any item that needs a customs form and is paid only with stamps must be presented at a counter (DMM 703.2.5.2).
- Hazmat: restricted hazardous materials can't be paid with stamps at all (USPS).
- Printed postage goes anywhere: labels from Click-N-Ship or a USPS kiosk can use any drop-off method (USPS).
What to do
- Buy the label online instead: commercial prices are lower and the package can go in a mailbox, a collection box or a pickup.
- If you use stamps, hand anything over 10 oz or 1/2 in. thick to the counter so it isn't returned to you.
Questions
Can I put a stamped package in a blue mailbox?
Only if it is less than 1/2 in. thick and weighs less than 10 oz. A heavier or thicker stamped package left in a collection box is returned to you; it has to go over a Post Office counter (USPS).
How many Forever stamps for a package?
Divide the postage by 82¢ and round up: 12 for a 4 oz Ground Advantage parcel to Zone 5 ($9.35 retail). Stamps pay retail prices, not the lower online ones.
Sources
Rates verified on from each official page below.
- USPS Notice 123, Price List (effective Oct 4, 2026)
- USPS Domestic Mail Manual 283: Ground Advantage commercial prices and eligibility
- USPS Domestic Mail Manual 604: postage payment, rounding and postage discrepancies
- USPS Domestic Mail Manual 703.2: overseas military and diplomatic mail (APO/FPO/DPO)
- USPS: How to Send a Package (domestic)
Free 1-page Reseller Cheat Sheet: fees on 8 platforms, Media Mail and stamp prices
What each platform takes from a $10, $25 and $50 sale, Media Mail 1-10 lb, Ground Advantage to Zones 1, 5 and 8, and the Forever stamp, on one printable page. The link appears as soon as you sign up.