How dimensional weight works
USPS charges a large, light parcel as if it were heavier. Once a parcel is over 1,728 cubic inches (one cubic foot), it is priced by whichever is greater: the actual weight, or length times width times height divided by 139. Each side is rounded up to a whole inch first, and the result is rounded up to a whole pound.
So a 14 by 14 by 14 inch box is 2,744 cubic inches, and it bills as 20 lb even if it holds a 2 lb jacket. Dropping to 12 by 12 by 12 brings it back under the limit, and it bills at 2 lb. A smaller box is often the cheapest thing you can do for your margin.
Why you see a range
USPS prices depend on distance as well as weight, and you rarely know the buyer's location when you price an item. The low end is the nearest zone and the high end is the farthest within the usual US zones. Far-flung addresses such as Palau and Micronesia cost more. Post office prices are what you pay at the counter, while the USPS commercial prices are a guide to what discounted online postage looks like. Marketplace labels have their own rates, so check the listing form for the real figure.
Weights between the rows in the table round up to the next listed weight, so a result can run slightly high. USPS prices effective October 4, 2026. These include USPS's temporary holiday increase, which ends January 16, 2027.
Size surcharges
- Longest side over 22 in, up to 30 in: add $4.50.
- Longest side over 30 in: add $10 on Ground Advantage or $21 on Priority Mail.
- Over 2 cubic feet: add $21 on Ground Advantage or $35 on Priority Mail.
- Tubes, rolls, cans, and wood or metal boxes: add $4.50.
Label rules by marketplace
- Poshmark. The buyer pays a flat $6.49 for a prepaid label covering up to 5 lb. You pay upgrades: $5 up to 10 lb, $10 up to 15 lb. Source
- Mercari. Prepaid USPS, UPS and FedEx labels, with lower prices when you enter dimensions and the parcel is within 1 cubic foot. Buyer-paid or seller-paid. Source
- Depop. A prepaid USPS label priced by parcel size, which Depop says the buyer pays. Depop publishes no price table. Source
- Vinted. The buyer chooses and pays for shipping at checkout. You use the prepaid label or QR code. Source
- eBay. Discounted labels you pay for, with the eBay standard envelope for light, flat items under 3 oz. Source
- Facebook Marketplace. Where offered, the label cost comes out of your payout, and you pay any weight overage. Not every seller has every shipping feature. Source
- Etsy. USPS labels at discounted volume rates, up to 70 lb, bought through Etsy. Source
- Whatnot. A prepaid label on every order, normally paid by the buyer, with weight adjustments charged to you. Source
Common questions
What is the dimensional weight divisor for USPS?
USPS divides length times width times height by 139 for parcels over 1,728 cubic inches. Some other sources quote a different divisor, but this is the figure in the USPS Domestic Mail Manual.
Is Ground Advantage or Priority Mail cheaper?
Ground Advantage is usually cheaper, and the gap widens with weight and distance. Priority Mail is faster, which may be worth it on a valuable or time-sensitive item.
Do these prices match what marketplaces charge?
Not exactly. Marketplace labels use their own negotiated or flat rates, listed by platform on this page where they publish them.