USPS shipping update

USPS now uses a 139 dimensional-weight divisor

Effective July 12, 2026 · Domestic Mail Manual revision

Large, light USPS packages can now be billed at a higher weight. Older calculators that still divide package volume by 166 understate the current dimensional weight.

What changed

• The dimensional-weight divisor changed from 166 to 139.
• Each package dimension is rounded up to the next whole inch before volume is calculated.
• The resulting dimensional weight is rounded up to the next whole pound.

Which packages are affected

USPS dimensional weight applies to eligible packages larger than one cubic foot — more than 1,728 cubic inches — mailed to Zones 1–9. USPS compares dimensional weight with actual scale weight and charges using the higher billable weight.

Worked example: 16 × 12 × 10 inches

The box is 1,920 cubic inches, so it exceeds the one-cubic-foot threshold. Under the old divisor, 1,920 ÷ 166 rounded up to 12 lb. Under the current rule, 1,920 ÷ 139 rounded up to 14 lb. That is a two-pound increase in dimensional weight even though the physical box and scale weight did not change.

Check a package before buying a label

Enter length, width, height, and actual weight in the shipping profit and DIM weight calculator. It applies the current USPS threshold and divisor and also supports UPS and FedEx comparisons.

Source

USPS — July 12, 2026 DMM revision (dimensional weight divisor and rounding). See all source links, verification dates, and rule versions in our methodology.