Shipping a big, light box costs more than its weight suggests. Enter the package dimensions and actual weight and this calculator applies each carrier's divisor and rounding rules to show the dimensional weight and the billable weight for UPS, FedEx, USPS, and DHL side by side. Divisors reflect published carrier rules as of September 2026, including the USPS change from 166 to 139 that took effect on July 12, 2026.
Shipping by the pallet instead? The pallet loading calculator works out how many cartons fit per layer. The unit converter handles inch, centimeter, pound, and kilogram conversions, and the invoice generator helps you bill the shipping cost on to a customer. Why 139, and what that divisor means as a density, is explained in the 139 divisor, explained.
Frequently asked questions
What is dimensional weight?
Dimensional (DIM) weight is a pricing rule carriers use so that large, light boxes pay for the space they take up in a truck or plane. The carrier multiplies length × width × height and divides by a number called the DIM divisor. If the result is more than the box actually weighs, you are billed for the DIM weight instead. A 16 × 12 × 8 inch box weighing 4 pounds has a DIM weight of 11.05 pounds at a 139 divisor, which carriers round up and bill as 12 pounds.
What DIM divisors do UPS, FedEx, USPS, and DHL use?
As of September 2026: UPS uses 139 for daily (account) rates and 166 for retail counter rates. FedEx uses 139 for Express and Ground. USPS switched from 166 to 139 on July 12, 2026, and only applies dimensional pricing to parcels over one cubic foot (1,728 cubic inches). DHL Express uses 5,000 cubic centimeters per kilogram, which is roughly 139 in imperial units. Carriers change these with their rate updates, so check your service guide before quoting a customer.
What is billable weight?
Billable weight is the weight your shipping price is actually based on: the larger of the actual weight and the dimensional weight, after rounding. US carriers round each measurement up to the next whole inch and round both weights up to the next whole pound, so a 4.1 pound box bills as 5 pounds. DHL rounds up to the next half kilogram. This calculator shows each carrier's rounded DIM weight, rounded actual weight, and which one wins.
Do carriers round up package dimensions?
Yes. UPS and FedEx began rounding every fractional dimension up to the next whole inch in August 2025, and USPS adopted the same rule in July 2026. A side measuring 12.2 inches is billed as 13 inches, which can add several pounds to the DIM weight of a large box. The rounding checkbox is on by default to match; turn it off to see the unrounded math. Measure the longest point of each side, including any bulge.
How can I lower my dimensional weight charges?
Use the smallest box that protects the item — trimming one inch from each side cuts DIM weight by roughly 15–25 % on common box sizes. Right-size cartons, use poly mailers for soft goods, and avoid excess void fill. Higher-volume shippers can often negotiate a larger divisor such as 166, 194, or 225 into their carrier contract; enter it in the custom divisor field to see the savings. For USPS, keeping a parcel at or under one cubic foot avoids DIM pricing entirely.