Dimensional Weight Calculator

Carriers charge for the space your package takes up, not just how heavy it is. Dimensional weight translates a box's volume into a weight equivalent, and you are billed on whichever is greater: actual weight or dimensional weight. Sellers shipping light but bulky items, like pillows, wreaths or lampshades, are often stunned the first time a 2-pound package bills at 9 pounds.

The math is simple: length times width times height divided by a divisor. UPS and FedEx use 139 for US domestic shipments and 166 for international. USPS applies dimensional weight to packages over one cubic foot with a divisor of 166. Carriers round the result up and bill the greater of the two weights, so there is no rounding in your favor.

Enter your box dimensions, actual weight and the right divisor to see your dimensional weight, billable weight, and which one the carrier will actually charge. If dimensional weight wins, the fix is physical: a smaller box, less void fill, or a poly mailer for soft goods. Shaving even an inch off each dimension can drop the billable weight by several pounds on large boxes.

This is an estimate using standard published divisors. Fuel surcharges, residential fees and special handling are separate line items on your carrier invoice.