Describe what goes inside and the calculator sizes the carton before it prices the trip.
What a shipping box costs today
Six paid listings sorted by the per-carton price, with the postal option parked at the bottom because its zero is conditional. Across the paid rows the spread is 83 cents, which matters at 500 boxes a month and barely registers at ten.
| Seller and item | Box size | Smallest purchase | Price per box |
|---|---|---|---|
| Uline S-4130, 200 lb test | 12 x 10 x 6 in | Bundle of 25 | $0.94 |
| Uline S-4125, 200 lb test | 12 x 12 x 12 in | Bundle of 25 | $1.09 |
| Staples 12106, 32 ECT | 12 x 10 x 6 in | Bundle of 25 at $31.39 | $1.26 |
| Home Depot medium moving box | 18 x 18 x 16 in | One box | $1.34 |
| U-Haul small moving box, bundle | 16-3/8 x 12-5/8 x 12-5/8 in | Bundle of 25 at $34.75 | $1.39 |
| U-Haul small moving box, single | 16-3/8 x 12-5/8 x 12-5/8 in | One box | $1.77 |
| USPS Postal Store, Priority Mail small box | 9-7/16 x 6-7/16 x 2-3/16 in | Pack of 10 | $0.00 |
Two things hide inside that table. The bundle sellers quote a low per-box number that only exists at 25 units, so the real question is whether 25 boxes of one size will move through your bench before the cardboard goes soft. And the USPS row is not a bargain in the ordinary sense, because that packaging carries a postage obligation with it; the ordering guide covers exactly what the $0.00 commits you to.
The cardboard is not the expense
Put the two tables side by side and the shopping question changes shape. A 94-cent carton carries a $13.52 label on a mid-length domestic lane, so the cardboard barely registers next to the postage.
| Carton, outer inches | Load | Cheapest service returned | Price |
|---|---|---|---|
| 12 x 10 x 6 | 5 lb | UPS Ground Saver | $13.52 |
| 12 x 12 x 12 | 15 lb | USPS Ground Advantage | $17.01 |
| 18 x 14 x 10 | 5 lb | UPS Ground Saver | $20.50 |
| 20 x 16 x 12 | 25 lb | FedEx Ground Economy | $28.77 |
Notice the third row. A 5 lb load in an 18 by 14 by 10 carton costs $6.98 more than the same 5 lb in a 12 by 10 by 6 one, which is more than eight times the 83-cent spread between the cheapest and dearest box in the shopping table. Buying the right size beats buying the cheap size by a wide margin, and our box ladder prices nine stock cartons so you can pick before you order.
Buy the strength, not just the size
Uline sells the 12 by 10 by 6 in at 200 lb test and Staples sells the same footprint at 32 ECT, and the two ratings answer different questions. Our box strength page decodes both stamps and shows which weights each one is rated for.
Retail wins when you need one box
Nobody should buy 25 cartons to send a single parcel. Home Depot and U-Haul both list singles under two dollars, and the trip to the store costs less than the storage space a bundle takes up.
Cardboard you already own is still free
Grocery and liquor back rooms, plus the parcels arriving at your own door, cover most low-volume needs at zero cost. The no-cost sources page lists them and the reuse rules that come with them.
Buying boxes, answered
Where is the cheapest place to buy shipping boxes?
A packaging supplier, if you can take the minimum bundle. On 2026-07-28 Uline listed a 12 by 10 by 6 inch 200 lb test carton at $0.94 per box in bundles of 25, and Staples listed the same footprint at $1.26 per box in bundles of 25. Buying one box at a time costs more everywhere.
Can I buy just one shipping box?
Yes, from moving and home improvement retailers. On 2026-07-28 U-Haul listed its small moving box at $1.77 for one and $34.75 for a bundle of 25, and Home Depot listed an 18 by 18 by 16 inch moving box at $1.34 each. The premium for a single is real but small.
Is it worth buying boxes when USPS gives them away?
Only when you want the postage that comes with them. USPS lists Priority Mail and Priority Mail Express packaging at $0.00 in its Postal Store, and usps.com states that if you use a Priority Mail box, you have to pay for Priority Mail service. A purchased carton leaves the service choice open.
How much does the box matter next to the postage?
Very little. A 12 by 10 by 6 inch carton holding 5 lb quoted $13.52 from Newark, NJ 07102 to Atlanta, GA 30303 on 2026-07-28, about fourteen times what the cardboard cost. Choosing the right size saves far more than choosing the cheap cardboard.