Dimensional Weight Calculator
Enter your box size and weight to see the billable weight carriers will charge, including the new USPS rules from July 2026, and compare carriers side by side.
- New July 2026 USPS rules
- UPS, FedEx and Amazon too
- Checked Oct 16, 2026
This box is 1 cubic foot or smaller, so USPS charges actual weight.
Details
Same box, every carrier
| Carrier | Measured as | Dim weight | Billable |
|---|---|---|---|
| UPS | 14 × 12 × 10 | 12.1 lb | 13 lb |
| FedEx | 14 × 12 × 10 | 12.1 lb | 13 lb |
| USPS | 14 × 12 × 10 | not applied | 4 lb |
| Amazon FBA | 14 × 12 × 10 | 12.1 lb | 13 lb |
How it's calculated
Dimensional weight = length × width × height ÷ divisor. Each carrier first rounds the measurements its own way: USPS rounds every side up to the next inch, UPS and FedEx round to the nearest inch.
Billable weight is the higher of dimensional and actual weight, rounded up to the next pound (or half kilogram for metric). USPS only uses dimensional weight for boxes over 1 cubic foot (1,728 cubic inches).
Carrier rules last reviewed 2026-10-16.
Questions sellers ask
What is dimensional weight?
Dimensional (DIM) weight is a weight carriers calculate from a box’s size: length × width × height ÷ a divisor. You pay for whichever is higher, the dimensional weight or the actual weight. It stops light but bulky boxes from shipping cheaply.
What is the USPS dimensional weight divisor in 2026?
Since July 12, 2026, USPS uses a divisor of 139 (down from 166) for Priority Mail, Priority Mail Express, Ground Advantage and Parcel Select. It applies only to boxes larger than 1 cubic foot, and every fraction of an inch is now rounded up.
What divisor do UPS and FedEx use?
UPS and FedEx use 139 for daily rates, and can apply dimensional weight to boxes of any size. Retail and negotiated accounts may use different divisors, so check your rate agreement.
How do I calculate dimensional weight in cm and kg?
Multiply length × width × height in centimetres and divide by 5000, the divisor most international express carriers use. A 40 × 30 × 20 cm box weighs 4.8 kg dimensionally.
How can I lower my dimensional weight?
Use the smallest box that fits, cut down or replace tall boxes, and switch to padded mailers or poly bags for soft items. The calculator shows the largest box volume that would still bill on actual weight.