Order in one batch, not weekly
With a week or more of lead time, a single order of the two sizes you actually use beats topping up. Keep the packs flat and dry; corrugated left in a damp garage loses stiffness before you get to it.
Postal Store
Free USPS boxes and how to order them
USPS lists its Priority Mail and Priority Mail Express packaging at $0.00 in the Postal Store, ships it to your address at no charge, and asks only that the parcel travel on the matching service. Plain cartons, tape and cushioning are not part of the deal, and this page separates the two piles.
Catalog read 2026-07-28Pack sizes listedService rules quoted
The box is the easy part
Rates for the packed carton come back in one pass, across carriers, with no account.
What the Postal Store sends at no charge
You order these the same way you would order anything else online, except the total stays at zero and there is no card to enter. Quantities are fixed by the listing, so a pack of 25 is a pack of 25 whether you need 25 or three.
| Item as listed | Pack quantities offered | Listed price |
|---|---|---|
| Priority Mail Small Box | Pack of 10 or 25 | $0.00 |
| Priority Mail Large Box | Pack of 10 or 25 | $0.00 |
| Priority Mail Side-Loading Large Box | Pack of 10 or 25 | $0.00 |
| Priority Mail Flat Rate Medium Box | Single, pack of 10 or 25 | $0.00 |
| Priority Mail Flat Rate Side-Loading Medium Box | Single, pack of 10 or 25 | $0.00 |
| Priority Mail Express Side-Loading Medium Box | Pack of 10 or 25 | $0.00 |
| Dual-Use Priority Mail and Priority Mail Express Small Tube Box | Pack of 10 or 20 | $0.00 |
| Priority Mail Tyvek Envelope | Pack of 10 | $0.00 |
| Priority Mail MILI-PAC Envelopes | Pack of 10 | $0.00 |
| Priority Mail Shipping Labels | Pack of 10 | $0.00 |
| Priority Mail Labels | Roll of 1,000 | $0.00 |
| Caution Heavy Labels | Roll of 500 | $0.00 |
Lead time is the part people misjudge. USPS states that boxes and envelopes are delivered with your regular mail usually within 7 to 10 days, per usps.com, so ordering on a Friday for a Monday shipment does not work. Post Office lobbies carry the popular sizes on a rack for anyone who needs cardboard the same afternoon, and the wider no-cost roundup covers the non-postal sources as well.
The condition attached to every $0.00 box
If you use a Priority Mail box, you have to pay for Priority Mail service.usps.com/ship/packages, read 2026-07-28
Priority Mail Flat Rate shipping supplies may only be used to ship via Priority Mail Flat Rate.Postal Store product listing for the Priority Mail Flat Rate Medium Box, read 2026-07-28
Both sentences point the same way. The branding on the cardboard is a service commitment, not decoration, so a Priority Mail box cannot carry a cheaper Ground Advantage label and a flat-rate box cannot be sent at weight-based prices. Anyone whose parcel is slow and light needs plain cardboard instead, which is a purchase; the buying guide lists current per-box prices from five sellers. Our USPS packaging catalog works through when the branded box is still the better trade.
What the postage runs on those footprints
The cardboard costs nothing, so the only number worth comparing is the label. We cut three plain boxes to the flat-rate footprints, loaded each to 5 lb, and took the lowest live rate on one lane.
| Footprint | Outer inches | Cheapest service returned | Price |
|---|---|---|---|
| Small flat-rate size | 8.625 x 5.375 x 1.625 | UPS Ground Saver | $10.18 |
| Medium flat-rate size | 11 x 8.5 x 5.5 | USPS Ground Advantage | $12.05 |
| Large flat-rate size | 12 x 12 x 5.5 | UPS Ground Saver | $13.52 |
Set those against the counter prices USPS publishes for the branded versions in Notice 123, effective 2026-07-12: $13.65 for the small flat-rate box, $24.80 for the medium and $34.00 for the large. At 5 lb on this lane the plain-box route wins every row, and it wins the medium row by $12.75. Flat rate earns its keep on dense, heavy, long-distance loads, not on the average parcel.
Labels and forms are on the same catalog
Blank Priority Mail label sheets, Certified Mail labels and Caution Heavy rolls all sit at $0.00 alongside the boxes. If you print at home you can skip them, but the heavy roll is worth having for anything over 50 lb.
The rest of the bench you buy
Tape, void fill and plain cartons never appear at $0.00 anywhere. Our tape guide and void fill guide both carry current listed prices so you can budget the bench properly.
USPS supply questions
Are USPS boxes really free?
Yes. The Postal Store listed Priority Mail and Priority Mail Express packaging at $0.00 when we read it on 2026-07-28, in fixed packs of 10 or 25 depending on the item, with no shipping charge. USPS states that boxes and envelopes are delivered with your regular mail usually within 7 to 10 days.
Can I use a Priority Mail box for USPS Ground Advantage?
No. The usps.com packages page states that if you use a Priority Mail box, you have to pay for Priority Mail service, and the Postal Store listing states that Priority Mail Flat Rate shipping supplies may only be used to ship via Priority Mail Flat Rate. A slow, light parcel needs a plain carton instead.
How many boxes can I order at a time?
The listing decides. When we read the Postal Store on 2026-07-28, most boxes offered a pack of 10 or a pack of 25, the flat-rate medium boxes also offered a single, and the small tube box offered a pack of 10 or 20. Labels came on rolls of 500, 600 or 1,000.
What shipping supplies does USPS not give away?
Plain unbranded cartons, packing tape, cushioning and void fill, poly mailers and scales. None of those appear at $0.00 in the Postal Store, and all of them are needed for weight-based services where a branded box would force you onto Priority Mail pricing.