How to calculate USPS Dimensional Weight in 2026

Multiply your package's length × width × height (in inches) to get the cubic volume, then divide by 166 (the USPS DIM divisor for domestic packages). The result is the dimensional weight in pounds. USPS charges whichever is greater — the actual scale weight or the DIM weight.

When does USPS use dimensional weight instead of actual weight?

USPS applies DIM weight pricing to Priority Mail and Priority Mail Express packages that exceed 1 cubic foot (1,728 cubic inches). If your package is lightweight but physically large, DIM weight will be higher — and that's what you pay for.

What is the USPS DIM divisor?

For domestic USPS shipments the divisor is 166. For international packages it's 139. The lower the divisor, the more aggressively large packages are penalized — so international DIM is stricter.

How can I reduce my USPS DIM weight charges?

Use the smallest box that safely fits your product. Avoid excessive void fill that increases box size. If your item is dense and heavy, actual weight will likely win anyway — but for light, bulky items like pillows or foam, right-sizing the box is critical.

USPS Dimensional Weight Calculator

Calculate USPS dimensional weight (DIM) for your package. Find out if you'll be charged for actual weight or dimensional weight — and avoid shipping surprises.

Type

Package Volume (cu in)

Actual Weight (lbs)

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Frequently asked questions

USPS Dimensional Weight (DIM) Calculator 2026 — Billable Weight Checker

Shipping a large but lightweight package? USPS doesn't always charge by the scale — for Priority Mail packages over 1 cubic foot, they calculate dimensional weight (DIM weight) using your box dimensions. If your box is airy, you'll pay for the space it takes, not just its mass. Enter your package volume and actual weight to instantly see which one USPS will bill you for.

DIM vs actual weight comparison

Instantly see both calculated DIM weight (volume ÷ 166) and your actual scale weight, with the billable weight highlighted.

Domestic & international

Toggle between the domestic divisor (166) and the stricter international divisor (139) used for USPS international packages.

Avoid shipping surprises

Check before you ship — right-sizing your box can save money on every package when DIM weight applies.

Use this calculator before printing a USPS label so you know the true shipping cost. For FBA sellers and e-commerce businesses shipping many packages, DIM weight awareness can significantly cut your shipping costs.

Fee rates verified and updated April 2026. Rates may change — verify directly with the platform before transacting.