USPS dimensional weight calculator

From 12 July 2026, USPS divides by 139 for Priority Mail Express, Priority Mail, USPS Ground Advantage and Parcel Select Destination Entry parcels over 1 cubic foot (1,728 in³) to zones 1–9. Smaller parcels are priced on their scale weight.

Divisor
139 in³/lb from 12 July 2026 (166 before)
Applies
Only to parcels over 1,728 in³ (1 ft³), zones 1–9
Each side
Rounded up to the next whole inch, before the 1,728 in³ test
Weight
The greater of scale and dimensional weight, up to the next whole lb
Not covered
Cubic and Flat Rate pricing, nonstandard fees, international mail
Source
USPS Postal Bulletin 22705; USPS DMM 123 §1.3

Check one carton

Billable weight14 lbBilled on volume: 5 lb more than the scale weight alone.

  1. Each side rounded up to a whole in: 16 × 12 × 10 in = 1,920 in³.
  2. That is over 1,728 in³ (1 cubic foot), so dimensional weight applies.
  3. Dimensional weight: 1,920 ÷ 139 = 13.81 lb.
  4. Scale weight: 9 lb.
  5. Billed: the greater of the two, rounded up to a whole lb = 14 lb.

Open this carton in the multi-carton calculator to add more boxes, compare divisors or export a CSV.

USPS rule as published; account rates can use another divisor. No surcharges or prices.

The USPS rule, step by step

  1. Measure the outside of the parcel and round each side up to the next whole inch (12.1 in counts as 13).
  2. Multiply the three sides. If the result is 1,728 in³ or less, dimensional weight does not apply: the parcel is priced on its scale weight.
  3. Over 1,728 in³, divide by 139 and round up to the next whole pound.
  4. The higher of that and the scale weight, rounded up to a whole pound, is the weight the price is looked up for.

Around the 1 cubic foot line

ParcelSides rounded upDimensional weightBilled
12 × 12 × 12 in, 5 lb12 × 12 × 12 = 1,728 in³Not applied5 lb
12 × 12 × 12.5 in, 5 lb12 × 12 × 13 = 1,872 in³13.47 lb14 lb
16 × 12 × 10 in, 9 lb16 × 12 × 10 = 1,920 in³13.81 lb14 lb
20 × 16 × 12 in, 25 lb20 × 16 × 12 = 3,840 in³27.63 lb28 lb

A 12-inch cube is exactly 1,728 in³, which is not over the limit, so it is priced on its 5 lb. Half an inch more on one side makes it 12 × 12 × 13 in = 1,872 in³, and the same 5 lb parcel is billed 14 lb. Fractions matter because each side is rounded up before the 1,728 in³ test.

Cartons measured in centimetres

Convert to inches first, then round up: 40 × 30 × 25 cm is 15.75 × 11.81 × 9.84 in, billed as 16 × 12 × 10 in = 1,920 in³, over the limit, so 13.81 lb dimensional weight against 4 kg (8.82 lb) on the scale: 14 lb. Choose centimetres and kilograms in the calculator above and it does this for you.

What this does not cover

Several parcels?

The multi-carton calculator applies the same USPS rule to up to 40 carton lines, shows which are over 1,728 in³ and exports a CSV. To compare the same parcels with a carrier that charges dimensional weight at every size, use the UPS or FedEx rule.

Sources

USPS Postal Bulletin 22705 (effective 12 July 2026); USPS DMM 123, section 1.3. Checked 28 October 2026.

Related

Last updated: 28 October 2026. Billable weight only: surcharges, minimum charges and your negotiated rates are not included.