Dimensional weight calculator

Why carriers charge by dimensional weight

This compares scale weight with volume divided by a number you choose. Use it to compare carton sizes under your shipping agreement. It does not select or apply carrier-specific rules.

A worked example

Suppose you ship a lightweight wool blanket in a 20 × 16 × 12 inch box. On the scale, the package weighs only 15 lbs. For this example, you enter a divisor of 139 and round up to whole pounds:

• Volume: 20 × 16 × 12 = 3,840 cubic inches (2.22 cubic feet).
• Dimensional weight: 3,840 / 139 = 27.63 lbs.
• Comparison: Because 27.63 lbs is higher than the 15 lb actual scale weight, the carrier bills for 27.63 lbs, rounded up to the nearest whole pound (28 lbs).
• Bottom line: You are billed for 28 lbs of shipping, paying for an extra 13 lbs of air. Reducing the carton dimensions by just 2 inches in each direction would lower billable weight to 19 lbs under these same assumptions. This does not calculate postage.

Common mistakes

Measure the outside of the packed box, including bulges. Check your shipping agreement for dimension rounding, divisor, minimum volume, weight rounding and exceptions. This calculator always applies dimensional weight; it does not decide whether your service requires it.