FedEx dimensional weight calculator

FedEx Ground, Home Delivery, Express (US). Divisor 139.

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FedEx · divisor 139

FedEx Ground, Home Delivery, Express (US)

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 FedEx calculates billable weight

Round each side up to the next whole inch.
Multiply length × width × height in inches.
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

139 applies to all packages.
Since August 2025 fractional inches round up to the next whole inch.

Sources: FedEx: how to calculate DIM weight. Last verified 2026-09-30. See our methodology.

FedEx 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	1 lb
6 × 4 × 4	1 lb
7 × 5 × 3	1 lb
8 × 8 × 8	4 lb
9 × 9 × 9	6 lb
10 × 8 × 4	3 lb
10 × 10 × 10	8 lb
12 × 8 × 4	3 lb
12 × 9 × 6	5 lb
12 × 10 × 8	7 lb
12 × 12 × 8	9 lb
13 × 10 × 5	5 lb
14 × 14 × 8	12 lb
15 × 12 × 10	13 lb
16 × 12 × 12	17 lb
17 × 11 × 8	11 lb
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

FedEx DIM weight questions

What is the FedEx dimensional weight divisor?

FedEx uses 139: multiply length x width x height in inches and divide by 139 to get dimensional weight in pounds.

Does FedEx 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.