The 1 cubic foot rule
Postage for parcels over 1,728 in³ is the greater of actual or dimensional weight. At exactly 1,728 in³ the rule does not trigger, and USPS bills the actual weight.
USPS Domestic Mail Manual 223.1.4USPS dimensional weight calculator
USPS is the one carrier here with a size floor: dimensional weight applies only when a parcel's volume exceeds 1 cubic foot (1,728 in³). Over that line, USPS divides by 139, the divisor it adopted on July 12, 2026. Enter the packed size and weight and this page applies the floor first, then the divisor. The dimensional weight calculator shows how the same box bills at the other carriers.
Your package
in
in
in
lb
Fractions work: 27½ or 3-1/8. Results update as you type.
Billable weight at USPSEstimate
– lb
Threshold meter
Estimate only. USPS's measurement governs billing. Weight only, never a price.
Dispute evidence checklist
If the carrier's bill differs from this estimate, gather this evidence before you dispute:
- Photo of the packed box or pallet with a tape measure across each side
- Photo of the package on a scale showing the weight
- The label or bill of lading copy with the dimensions and weight you entered
- The carrier's adjustment notice with the recorded dimensions
- A screenshot or printout of this result, with the date
- Photos of all six sides if the carrier claims damage or a nonrectangular shape
- Your scale and tape calibration notes, if you have them
How we got there
The USPS rules behind this result
Divisor 139 since July 12, 2026
USPS replaced 166 with 139 for Priority Mail Express, Priority Mail, Ground Advantage and Parcel Select, in both the retail and commercial sections of the DMM. Older pages still teaching 166 or a 194 divisor are out of date.
USPS DMM, current editionRounding and the 70 lb cap
Each dimension rounds up to the next whole inch (DMM 604.7.0), and the DIM weight rounds up to the next whole pound. If the DIM weight passes 70 lb, the 70-lb price applies.
USPS Domestic Mail Manual 223.1.4Other carriers
The same package can bill differently somewhere else. The dimensional weight calculator compares all five side by side, and the divisors dataset lists every rule in one table.
Questions
When does USPS charge dimensional weight?
Only when the parcel's volume exceeds 1 cubic foot (1,728 in³), on Priority Mail Express, Priority Mail, Ground Advantage and Parcel Select. Flat Rate products are priced by the box and are exempt.
What is the USPS DIM divisor in 2026?
139. It changed from 166 on July 12, 2026, under a final rule published in the Federal Register in May 2026. The current DMM sections for all four services state 139 for retail and commercial mailers.
How does USPS measure a nonrectangular parcel?
The DMM applies a 0.785 adjustment factor to the volume of nonrectangular parcels such as tubes and rolls before the divisor is applied. Measure the length and the diameter, and the manual's formula does the rest.
Sources
- USPS Domestic Mail Manual 113.1.4, 123.1.4, 133.1.4, 213.1.4, 223.1.4, 283.1.4 (dimensional weight)
- USPS Domestic Mail Manual 604.7.0 (rounding of measurements)
- Federal Register final rule, May 15, 2026 (divisor change effective July 12, 2026)
Rules last checked November 12, 2026 · How we check every figure