Dimensional Weight Calculator
Find the dimensional (DIM) weight of a box and the billable weight a carrier will charge for, using current UPS, FedEx, USPS, DHL and air cargo rules.
- Billed on
- Dimensional weight
- Actual weight
- Measured as
- Volume
- Most volume at this weight
- Paying for Air
Shipment
Packages you add are saved in this browser. Each package is billed on its own billable weight.
| Qty | Carrier | Size | Actual | DIM | Billable Each | Billable Total | Remove |
|---|---|---|---|---|---|---|---|
| No packages yet. Enter a box above and choose Add to shipment. | |||||||
How Dimensional Weight Works
Carriers charge for the space a package takes up, not just what it weighs. They figure a dimensional weight from the box size and bill whichever is greater, the dimensional weight or the actual weight. That larger number is the billable weight.
UPS and FedEx round every side up to the next whole inch before multiplying (a side of 11.1″ counts as 12″), and round both weights up to the next whole pound. USPS adopted the same 139 divisor and the same rounding on July 12, 2026, but only applies dimensional weight to packages larger than one cubic foot (1,728 cubic inches).
Worked Example
A 12″ × 12″ × 12″ box weighs 8 lb. Its volume is 1,728 cubic inches. With UPS or FedEx, 1,728 ÷ 139 = 12.43, which rounds up to a dimensional weight of 13 lb. Since 13 lb is more than 8 lb, the box bills at 13 lb, and you pay for 5 lb of air. With USPS the same box is exactly one cubic foot, not larger, so it bills at its actual 8 lb.
Divisors by Carrier
| Carrier | Divisor | Rounding |
|---|
Dimensional Weight of Common Boxes
| Box (in.) | Cubic In. | UPS / FedEx | UPS Retail | USPS |
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USPS shows “actual” where the box is one cubic foot or smaller, so it bills at its actual weight.
Tips to Lower Billable Weight
Use the smallest box that protects the product. Taking an inch off each side of a 12″ cube cuts its volume by almost a quarter. Because each side rounds up, a box that measures 12.1″ bills like a 13″ box, so check that flaps and tape don't push a side over a whole inch. The Most volume at this weight line shows how big a box can get before dimensional weight takes over.