No carrier hands out a free box built for a laptop. The Priority Mail flat rate boxes are fixed sizes meant for envelopes and small items, and a 15-inch machine with proper padding does not sit comfortably in the biggest one. What you actually need is one of four ordinary places nearby, or the box the laptop already came in.
The carrier prices the box you hand over. Where the box came from does not appear on the label.
Staples and Office Depot both stock a moving-and-shipping-box aisle with several rectangular sizes, sold individually. Look for something close to 18-20 inches on the long side so two inches of padding fits on every face without the laptop shifting.
The UPS Store and FedEx Office sell cartons over the counter and will pack the laptop for you if you'd rather not. That packing service is billed separately from postage, so decide up front whether you want the convenience or just the box.
Free, used, and hit-or-miss on size. A wine case or a case-of-cans box sometimes lands close to the right footprint; bring a tape measure before you commit to carrying one home.
If it is still around, this is usually the best fit there is. Float it inside a slightly larger outer carton with padding on all six sides rather than shipping the retail box alone — that box was engineered for a pallet, not a conveyor belt.
USPS supplies Priority Mail flat rate boxes at no charge, ordered online and delivered with regular mail, per usps.com read 2026-08-19. The largest options are the Medium Flat Rate Box in its side-loading style at 14 x 12 x 3.5 inches outside, and the Large Flat Rate Box at 12.25 x 12 x 6 inches. Neither gives a 15-inch laptop the two inches of padding on every side our packing guide recommends, and Flat Rate pricing only applies inside USPS's own packaging in the first place — put the laptop in a Staples box instead and you are quoted by weight and size like any other parcel.
That is not a loss. A laptop rated by weight and size, rather than jammed into an undersized flat rate box, is usually the cheaper and safer outcome anyway once you compare the numbers below.
We described “15-inch laptop in original retail box, double-boxed with padding for shipping” to the SMKlog calculator on 2026-08-19, sized at 20 x 15 x 5 inches and 10 lb, from Berkeley Heights, NJ 07922 to Denver, CO 80202. Every figure below is the full checkout total for that box.
| Carrier | Service | Price | Window |
|---|---|---|---|
| USPS | Ground Advantage | $21.25 | 4-5 business days |
| FedEx | Smart Post | $22.05 | 6-7 business days |
| UPS | Ground Saver | $22.08 | 5 business days |
| UPS | Ground | $22.17 | 5-6 business days |
| FedEx | Ground | $33.25 | 5-6 business days |
Cheapest on this run was USPS Ground Advantage at $21.25, and the top four services landed within about a dollar of each other — for a box this size the carton itself, not the carrier badge, is what moves the price. Read the full method for cutting a laptop box down to size in the laptop packing guide, which also covers the battery declaration step at checkout.
Four places usually have one: an office supply store's moving-box aisle, a shipping-carrier store that sells cartons by the piece, a grocery or liquor store's free used boxes if the size happens to work, or the laptop's own retail box if you kept it. None of them are laptop-specific; you are picking the closest fit and adding padding.
Barely, and only the largest one. USPS lists the Medium Flat Rate Box (side-loading style) at 14 x 12 x 3.5 inches outside and the Large Flat Rate Box at 12.25 x 12 x 6 inches, per usps.com read 2026-08-19. A 15-inch laptop plus the two inches of padding on every side our packing guide recommends does not fit either one with room to spare, and Flat Rate pricing does not apply outside USPS's own boxes in any case.
Yes, and it is usually the best option you have. Float the closed retail box inside a slightly larger outer carton with padding on all six sides rather than handing the retail box to the carrier bare — it is built for pallet transport, not a sorting belt.
Yes, both carry a range of carton sizes over the counter and will pack the laptop for you for a separate fee on top of the box. That is a different charge from the shipping label itself — buy the box there if it is convenient, then price the label wherever rates are best.
On a live check, a 15-inch laptop double-boxed to 20 x 15 x 5 inches and 10 lb quoted $21.25 on USPS Ground Advantage, rising to $33.25 on FedEx Ground, Berkeley Heights, NJ to Denver, CO on 2026-08-19. That is the whole checkout total for that box and route; a different laptop or a different route moves the number.