Dimensional weight calculator
As of July 12, 2026, USPS uses divisor 139 (down from 166). All fractional inches round up before the calculation.
Calculate DIM weight under the current rule
Enter dimensions above to calculate
USPS DIM applies to packages over 1,728 in³ (1 cubic foot). UPS and FedEx apply DIM to all packages. Pre–Jul 12 column rounds fractional dimensions down; post–Jul 12 column rounds them up, per the current USPS rule.
How DIM weight works
Carriers bill the greater of actual weight or DIM weight. DIM weight only applies to packages over 1,728 cubic inches (1 cubic foot) for USPS. For UPS and FedEx, it applies to all packages.
Entering package dimensions in Covantra runs this calculation per carrier automatically, so the rate shown already reflects whichever weight is billable. Enter a package
The July 2026 rounding change
A 13.1 × 12.3 × 11.9 inch box previously rounded down to 13 × 12 × 11 inches (1,716 in³) — just under the 1-cubic-foot DIM threshold, so DIM weight didn't apply at all. Under the July 12 rule, the same box rounds up to 14 × 13 × 12 inches (2,184 in³), crossing the threshold and setting a 15.7 lb billable floor where none applied before.
This rounding change is one of three USPS rate events landing in 2026. See the full 2026 rate change cascade → Or check which USPS service fits your package once you know its billable weight in the USPS services guide →
Frequently asked questions
- What is the USPS DIM weight change in July 2026?
- Effective July 12, 2026, USPS reduced its DIM weight divisor from 166 to 139 for packages over 1,728 cubic inches (1 cubic foot). The same package now calculates a higher dimensional weight — a 14×12×11 inch box previously calculated as 11.1 lbs DIM; after July 12 it calculates as 13.3 lbs DIM. USPS also changed dimension rounding: every fractional inch now rounds UP to the next whole inch before the DIM calculation.
Compare all carriers before your next shipment
See USPS, UPS, FedEx, Canada Post, Purolator, and more side by side — with known surcharges and DIM weight calculated before you print.