USPS dimensional weight calculator

Priority Mail, Priority Mail Express, Ground Advantage, Parcel Select. Divisor 139, in effect since July 12, 2026.

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USPS · divisor 139

Priority Mail, Priority Mail Express, Ground Advantage, Parcel Select

Billed on dimensions

Billable weight

22lb

You pay for 14 lb of air on every box.

Billed sides: 18 × 14 × 12 in
Volume ÷ 139: 3,024 → 21.76

A box 1 inch smaller on every side bills 4 lb less.

Same box, other carriers
USPS	÷139	22 lb
UPS	÷139	22 lb
FedEx	÷139	22 lb
UPS Retail	÷166	19 lb
DHL Express	÷5000	10 kg

How USPS calculates billable weight

Round each side up to the next whole inch.
Multiply length × width × height in inches.
If the result is 1,728 cubic inches or less, stop: you pay actual weight.
Divide by 139 and round up to the next whole pound.
Compare with the actual weight (also rounded up). The larger number is billed.

Worked example

A box measuring 18.3 × 14 × 11.6 in that weighs 7.2 lb is billed as 19 × 14 × 12 in. That is 3,192 cu in ÷ 139 = 22.96, rounded up to 23 lb, which is billed instead of the actual weight.

Rule notes

Divisor changed from 166 to 139 on 12 July 2026.
Dimensional weight only applies to packages larger than 1 cubic foot (1,728 cu in).
Fractional inches now round up to the next whole inch, which can push a box over the 1 cubic foot line.

Sources: DCL: USPS DIM weight changes, July 12 2026, Ordoro: USPS shipping changes 2026. Last verified 2026-09-30. See our methodology.

USPS DIM weight by box size

If your packed box weighs less than this, you are billed for this weight anyway.

Box (in)	DIM weight
4 × 4 × 4	actual weight only
6 × 4 × 4	actual weight only
7 × 5 × 3	actual weight only
8 × 8 × 8	actual weight only
9 × 9 × 9	actual weight only
10 × 8 × 4	actual weight only
10 × 10 × 10	actual weight only
12 × 8 × 4	actual weight only
12 × 9 × 6	actual weight only
12 × 10 × 8	actual weight only
12 × 12 × 8	actual weight only
13 × 10 × 5	actual weight only
14 × 14 × 8	actual weight only
15 × 12 × 10	13 lb
16 × 12 × 12	17 lb
17 × 11 × 8	actual weight only
18 × 14 × 12	22 lb
18 × 18 × 18	42 lb
20 × 14 × 10	21 lb
22 × 18 × 12	35 lb
24 × 18 × 16	50 lb
24 × 24 × 24	100 lb

USPS DIM weight questions

What is the USPS dimensional weight divisor?

USPS uses 139: multiply length x width x height in inches and divide by 139 to get dimensional weight in pounds. It changed from 166 on 12 July 2026.

Does USPS round dimensions up?

Yes. Each side is rounded up to the next whole inch before multiplying, so an 11.1 inch side is billed as 12 inches. The resulting weight is then rounded up to the next pound.

Does USPS DIM weight apply to small boxes?

No. USPS only applies dimensional weight to packages larger than 1 cubic foot (1,728 cubic inches). A 12 x 12 x 12 inch box is billed on actual weight, but a 12.25 inch cube rounds up to 13 inches per side and is billed dimensionally.