Dimensional Weight Calculator

Work out dimensional and billable weight for USPS, UPS and FedEx from a box’s size and weight.

Units

Inches and poundsCentimetres and kg

USPS bills 15 lb · dim 15 lb

Length

Width

Height

Actual weight

Not a rectangular box (tube, roll, odd shape)USPS multiplies the volume by 0.785. Measure the longest points.

Carrier to show

Priority Mail and USPS Ground Advantage. The table below compares every carrier.

Billable weight

USPS bills 15 lb, the dimensional weight, not the 4 lb actual weight.

15 lb

Sides usedrounded up to the next inch	18 × 14 × 8
Cubic inches	2,016
Dimensional weight÷ 139, rounded up	15 lb
Actual weightrounded up to the next pound	4 lb
Billable weight	15 lb

Every carrier for this parcel

Carrier	Divisor	Cubic in	Dim weight	Billable
USPSPriority Mail and USPS Ground Advantage	139	2,016	15 lb	15 lb
UPS Daily RatesDaily Rates (business account)	139	2,016	15 lb	15 lb
UPS Retail RatesRetail Rates (The UPS Store, ups.com without an account)	166	2,016	13 lb	13 lb
FedExUS domestic	139	2,016	15 lb	15 lb

US domestic packages. Rates are charged on the billable weight; check your carrier’s rate guide or account for the price.

Runs in your browserNo uploadLast verified 2026-10-30Sources: USPS Domestic Mail Manual, UPS, FedEx

How it works

Enter the outside length, width and height of the package and what it weighs, in inches and pounds or centimetres and kilograms. The calculator works out the dimensional weight and the billable weight for USPS, UPS and FedEx at once, using each carrier’s own rules, linked below the calculator.

Sides. Centimetres are converted at 2.54 to the inch. USPS then rounds each side up to the next whole inch, FedEx rounds each side to the nearest inch, and UPS uses the sides as measured. The result shows the sides each carrier ends up with.

Dimensional weight. The sides are multiplied to give cubic inches, then divided by the carrier’s divisor: 139 for USPS, UPS Daily Rates and FedEx, 166 for UPS Retail Rates. Any fraction is rounded up to the next pound. USPS only applies it to parcels over 1,728 cubic inches, and multiplies the volume of a tube or odd shape by 0.785 first.

Billable weight. Each carrier charges for the greater of the dimensional weight and the actual weight. USPS rounds the actual weight up to the next pound for its pound-based prices; kilograms are converted at 0.45359237 to the pound. If a USPS parcel’s dimensional weight is over 70 lb, the 70-pound price applies.

Comparing carriers. The table under the calculator lists every carrier for the same parcel, so you can see where a box crosses a pound or the USPS cubic-foot line. Pick a carrier to see its working in full, and copy a link to share the exact numbers.

Example

An 18 × 14 × 8 inch box of cushions that weighs 4 lb, shipped within the US.

Carrier	Working	Dim weight	Billable
USPS	2,016 ÷ 139 = 14.5	15 lb	15 lb
UPS Daily Rates	2,016 ÷ 139 = 14.5	15 lb	15 lb
UPS Retail Rates	2,016 ÷ 166 = 12.1	13 lb	13 lb
FedEx	2,016 ÷ 139 = 14.5	15 lb	15 lb

Every carrier charges more than three times the actual weight. In a 16 × 12 × 6 inch box the same cushions come to 1,152 cubic inches: under the USPS cubic-foot line, so USPS charges the 4 lb actual weight, and 9 lb at FedEx.

Dimensional weight divisors in 2026

US domestic packages, from each carrier’s own guidance, checked 2026-10-30.

Carrier	Divisor	Rule
USPSPriority Mail and USPS Ground Advantage	139	Over 1 cubic foot (1,728 cubic inches): each side rounded up to the next inch, length × width × height ÷ 139, rounded up to the next pound. Non-rectangular parcels × 0.785 first. Above 70 lb dimensional weight, the 70-pound price applies.
UPSDaily Rates (business account)	139	Length × width × height ÷ 139, any fraction rounded up to the next whole pound. Billable weight is the greater of dimensional and actual weight.
UPSRetail Rates (The UPS Store, ups.com without an account)	166	Length × width × height ÷ 166, any fraction rounded up to the next whole pound. Billable weight is the greater of dimensional and actual weight.
FedExUS domestic	139	Each side rounded to the nearest whole inch, length × width × height ÷ 139, rounded up to the next pound. Billable weight is the greater of dimensional and actual weight.

FAQ

What is dimensional weight?

Dimensional weight, or DIM weight, is a weight worked out from the size of a package rather than what it weighs. Carriers charge for whichever is greater, the dimensional weight or the actual weight, because a large light box takes up as much space in a truck as a heavy one. That greater figure is the billable weight.

How do I calculate dimensional weight?

Multiply the length, width and height in inches, divide by the carrier’s divisor, and round up to the next whole pound. An 18 × 14 × 8 inch box is 2,016 cubic inches; divided by 139 that is 14.5, so 15 lb. If the box actually weighs 4 lb, the carrier charges for 15 lb.

What divisor do USPS, UPS and FedEx use?

USPS divides by 139 for Priority Mail and USPS Ground Advantage, under a Domestic Mail Manual rule revised in July 2026. UPS uses 139 for Daily Rates on a business account and 166 for Retail Rates. FedEx uses 139 for US shipments. A bigger divisor gives a lower dimensional weight.

When does USPS charge dimensional weight?

Only for parcels over one cubic foot, 1,728 cubic inches, after each side is rounded up to the next whole inch. Smaller parcels are charged on actual weight. For a tube or other non-rectangular parcel, USPS multiplies the volume by 0.785 first. If the dimensional weight is over 70 lb, you pay the 70-pound price.

Should I round the measurements?

Each carrier says something different. USPS rounds each side up to the next whole inch. FedEx’s US guidance rounds each side to the nearest whole inch. UPS’s guidance divides the measured cubic size without mentioning rounding each side. The calculator applies each rule, and the sides used are shown in the result.

How can I lower my dimensional weight?

Use the smallest box the product fits safely, since every inch on each side multiplies. Taking 18 × 14 × 8 down to 16 × 12 × 6 cuts the volume from 2,016 to 1,152 cubic inches, below the USPS one-cubic-foot line, and the FedEx dimensional weight from 15 lb to 9 lb. Poly mailers suit soft goods.