USPS Dimensional Weight Calculator

How USPS Calculates Dimensional Weight

Unlike commercial carriers that apply dimensional weight to all package sizes, USPS applies DIM weight rules primarily to Priority Mail and Ground Advantage packages that exceed 1 cubic foot (1,728 cubic inches) when shipped to Zones 5 through 9.

USPS Imperial DIM Formula & Divisor

When a package exceeds 1 cubic foot, USPS divides total cubic inches by a divisor of 166:

(Length × Width × Height) ÷ 166 = Dimensional Weight (lbs)

USPS Cubic Pricing vs. Standard DIM

For high-volume shippers utilizing commercial pricing tiers, USPS also offers Cubic Priority Mail, which bases rates directly on package volume tiers (up to 0.5, 1.0, 2.0 cubic feet) rather than standard weight calculations, often yielding substantial savings on heavy, small-form-factor boxes.