Enter a box's dimensions and its actual weight to see the billable weight UPS, FedEx, and USPS will charge — the greater of actual weight and dimensional (DIM) weight. When the box is too big for what it weighs, you're paying for air; this tool shows exactly when and by how much.
DIM divisor 139 · USPS change effective Jul 12, 2026Measure each side at its longest point; carriers round each dimension up per their tariff. UPS & FedEx US domestic daily rates always use divisor 139. USPS applies DIM weight only to packages over 1 cubic foot (1,728 in³).
Carriers bill the greater of your package's actual weight and its dimensional weight — a volume-based figure that stops light, bulky boxes from shipping cheap. Dimensional weight = (L × W × H in cubic inches) ÷ the carrier's DIM divisor, rounded up to the next whole pound. A smaller divisor means a higher DIM weight. Whichever number is larger is your billable weight.
| Carrier / service | DIM divisor (in³/lb) | When DIM applies | Effective |
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Dimensional Weight Calculator runs entirely in your browser. Inputs are evaluated with rules and constants taken from UPS / FedEx / USPS DIM Divisor 139 (Freight & logistics). Nothing is uploaded to a server for the calculation itself.
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Anyone who needs a fast, cited freight & logistics reference — especially operators who would otherwise dig through a handbook or regulation PDF mid-task.
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The tool is built from UPS / FedEx / USPS DIM Divisor 139. Regulations and agency tables can change — use the source link on this page to verify the latest official text.