Dimensional Weight Formula
Dimensional weight estimates how much space a package occupies. Carriers compare it with actual weight and usually bill whichever value is greater.
The formula
Dimensional weight = length x width x height / divisor
Inch/lb example: 16 x 12 x 10 inches = 1,920 cubic inches. With divisor 139, dimensional weight is 13.82 lb.
Cm/kg example: 40 x 30 x 25 cm = 30,000 cubic cm. With divisor 5000, volumetric weight is 6 kg.
Common mistakes
The most common mistakes are mixing inches and centimeters, using the wrong divisor, forgetting to compare against actual weight, and assuming a generic example overrides the carrier contract.
Use a carrier-specific calculator when possible, then confirm the final quote with the carrier or your account rate system.
Carrier calculators
Frequently asked
What is the dimensional weight formula?
Dimensional weight equals length x width x height divided by the carrier divisor. Compare the result with actual weight to estimate billable weight.
What divisor should I use?
Many FedEx and UPS inch/lb parcel examples use divisor 139. USPS currently uses 166 in ShipCalc before its tracked July 12, 2026 change. DHL-style cm/kg examples commonly use 5000.
Is dimensional weight the same as billable weight?
No. Dimensional weight is one calculated weight. Billable weight is usually the greater of dimensional weight and actual weight.