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Dimensional weight calculator: what will the carrier bill you for?
Enter your box size and weight. See the DIM weight and billable weight for UPS, FedEx and USPS side by side (139 divisor, 2026 rounding rules), plus how small the box needs to be to pay for actual weight only.
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FAQ
How is dimensional weight calculated?
Measure the box’s length, width and height, round each side up to the next whole inch, and multiply them. Divide the cubic inches by the carrier’s divisor (139 for UPS, FedEx and USPS) and round up to the next whole pound. The carrier bills the greater of that and the actual weight.
What is the DIM divisor for UPS, FedEx and USPS?
139 cubic inches per pound for all three on US domestic parcels. USPS changed from 166 to 139 on 12 July 2026 (USPS Postal Bulletin 22705). UPS and FedEx publish 139 in their rate and service guides (UPS, FedEx).
Does USPS use dimensional weight?
Yes, but only for parcels larger than 1 cubic foot (1,728 cubic inches) for Priority Mail Express, Priority Mail, USPS Ground Advantage and Parcel Select. Smaller parcels are priced by actual weight.
What is billable weight?
The weight the carrier charges you for: the greater of the actual weight (rounded up to the next pound) and the dimensional weight. A large, light box is billed by its size.
How do I calculate dimensional weight in cm and kg?
Multiply length × width × height in centimetres and divide by your carrier’s metric divisor (5,000 cm³/kg is a common one, but check your carrier’s rate guide), then use the custom row. For UPS, FedEx and USPS US shipments, this calculator converts your cm and kg to inches and pounds and applies the 139 rule.