USPS rule center

USPS Priority Mail dimensional weight

Effective date

2026-07-12

Formula version

usps-dim-2026.07-v1

Divisor

139

Last verified

8/31/2026

Who is affected

US ecommerce shippers comparing actual and dimensional weight. Carrier accounts and negotiated agreements may have additional terms.

Notes and limitations

For Zones 1–9. Rectangular parcels above one cubic foot use divisor 139. Nonrectangular parcels use an adjustment factor of 0.785 and divisor 166.