Large, lightweight parcels can be charged using dimensional weight. Compare a current box with an alternative to understand the effect of packaging volume. This calculator shows weight, not a live shipping price, and exposes the carrier-rule assumptions.
How to use this calculator
Choose inches/pounds or centimeters/kilograms. Enter a divisor compatible with that measurement system and your carrier agreement. Select how dimensions should be rounded, then enter the box dimensions and scale weight. An alternative box uses the same actual weight and rules.
Formula and assumptions
Dimensional weight = rounded length × rounded width × rounded height ÷ divisor, rounded up. Modeled billable weight is the greater of dimensional weight and actual weight rounded up. This version uses whole-pound or whole-kilogram increments.
Worked example
A 20 × 15 × 10 inch box with divisor 139 has a dimensional weight of 22 lb after rounding up. If it weighs 8 lb, modeled billable weight is 22 lb. An 18 × 12 × 8 inch alternative has 13 lb dimensional weight under the same rule, reducing billable weight by 9 lb.
Common questions
Which divisor should I use?
Check your service and rate agreement. UPS publishes 139 for Daily Rates and 166 for Retail Rates in its U.S. guidance. A metric input requires a compatible metric divisor; changing the unit selector does not convert dimensions.
Will this match my carrier invoice?
Your carrier may apply different dimension rounding, weight increments, thresholds, package minimums, or surcharges. Confirm the rules for your shipment. This comparison does not calculate rates or add fees.
Sources and rule checks
Platform-specific assumptions reviewed September 20, 2026. Verify the requirements that apply to your account before making changes.
