Dimensional Weight Calculator for FedEx, UPS and USPS

This dimensional weight calculator shows what a carrier will bill for a box that is light for its size. Dimensional weight (dim weight or volumetric weight) is length × width × height divided by the carrier's divisor. You pay for the billable weight: the greater of the actual weight and the dimensional weight.

Quick answer: in inches and pounds, FedEx, UPS (daily rates) and USPS divide by 139. In centimeters and kilograms, express couriers and most Canada Post services divide by 5000, and air cargo divides by 6000.

Imperial: dim weight (lb) = L × W × H in inches ÷ 139 (or 166)
Metric: dim weight (kg) = L × W × H in cm ÷ 5000 (or 6000)

The result is an estimate to help you pick a box and quote a price. Your carrier's current service guide and your contract decide the final charge.

Worked examples

• FedEx or UPS: a 20 × 16 × 12 inch box weighing 18 lb. 20 × 16 × 12 = 3,840 cubic inches. 3,840 ÷ 139 = 27.6, which rounds up to 28 lb. You pay for 28 lb, not 18 lb.
• USPS: a 16 × 12 × 10 inch box is 1,920 cubic inches. That is over one cubic foot (1,728 cubic inches), so dim weight applies: 1,920 ÷ 139 = 13.8, billed as 14 lb if the box weighs less. A 14 × 12 × 10 inch box is 1,680 cubic inches, under one cubic foot, so USPS bills the actual weight.
• Canada Post Expedited Parcel: a 40 × 30 × 20 cm box weighing 3 kg. 24,000 ÷ 5000 = 4.8 kg. On Regular Parcel (divisor 6000) the same box is 4.0 kg.
• International express: a 50 × 40 × 30 cm box weighing 8 kg. 60,000 ÷ 5000 = 12 kg.
• Air cargo: a pallet of 120 × 100 × 150 cm weighing 210 kg. 1,800,000 ÷ 6000 = 300 kg, so the airline charges 300 kg.

Dimensional weight divisors by carrier (2026)

A lower divisor gives a higher dim weight. Check your carrier's current guide, since divisors and rounding rules change and contracts can set their own.

Carrier and service	Inches and pounds	Centimeters and kilograms	When it applies
FedEx, US and international	139	5000	All packages
UPS, daily rates (business accounts)	139		All packages, domestic and international
UPS, retail rates (The UPS Store, counter)	166 domestic, 139 export		All packages
USPS Priority Mail, Ground Advantage, Parcel Select	139 (166 for non-rectangular parcels)		Only parcels over 1 cubic foot (1,728 in³)
Canada Post Priority, Xpresspost, Expedited, US and international	139	5000	All parcels
Canada Post Regular Parcel	166	6000	All parcels
International express couriers (DHL Express and others)		5000	All packages
Air cargo (IATA standard)	about 166	6000	All shipments

The two systems line up: 139 in³/lb is about 5000 cm³/kg, and 166 in³/lb is about 6000 cm³/kg. So 1 CBM counts as 200 kg on a 5000 divisor and 166.67 kg on a 6000 divisor.

FedEx dimensional weight

FedEx divides the cubic inches by 139 for US and international packages, or the cubic centimeters by 5000. Pick the 139 divisor in the calculator.

UPS dimensional weight

The UPS Rate and Service Guide for daily rates rounds each side to the nearest whole inch, divides the cubic size by 139 and rounds any fraction up to the next pound. Retail rates, the ones you pay at a UPS counter, use 166 for US domestic packages and 139 for exports.

USPS dimensional weight

USPS only charges dim weight on parcels larger than one cubic foot. Round each side up to the next whole inch and multiply. If the result is over 1,728 cubic inches, divide by 139 and round up (non-rectangular parcels use 166). USPS used 166 for all parcels before, so older calculators now show a weight that is too low. Dim weight above 70 lb is charged at the 70 lb price.

Canada Post dimensional weight

Canada Post calls it volumetric equivalent weight. It divides by 5000 (cm) or 139 (inches) for Priority, Xpresspost, Expedited Parcel and all US and international parcels, and by 6000 or 166 for Regular Parcel. Choose "Custom divisor" in the calculator and enter the number for your service.

Dimensional weight vs volumetric weight vs chargeable weight

Dimensional weight and volumetric weight are the same thing. US carriers say "dim weight", while airlines and European couriers say "volumetric weight". Chargeable weight (UPS and FedEx say "billable weight") is the number on your invoice: the greater of the actual weight and the dim weight.

How carriers round

Carriers round before they bill, so the invoice can be a little higher than the exact figure. USPS rounds each side up to the next whole inch. The UPS daily rate guide rounds each side to the nearest whole inch. All three US carriers round the final weight up to the next whole pound, and couriers that bill in kilograms usually round up to the next 0.5 kg. Measure the packed box at its widest point, bulges included.

How to lower dimensional weight

• Use the smallest box that protects the goods. Taking 5 cm off each side of a 50 × 40 × 30 cm box (to 45 × 35 × 25 cm) cuts the dim weight from 12 kg to 7.9 kg on a 5000 divisor.
• Keep USPS parcels under one cubic foot. At 1,728 cubic inches or less, USPS bills the actual weight only.
• Ship light, bulky goods by sea. Sea LCL counts 1 CBM as 1000 kg, so volume costs far less than by air. Compare both in the CBM calculator.
• Consolidate small parcels into one carton or pallet where the service allows.
• Ask about the divisor. High volume shippers can often negotiate it in their carrier contract.

Put the final weights and sizes on the commercial invoice and the air waybill. A gap between declared and measured sizes is a common reason for extra charges. Have sizes in cubic feet? Convert them with the CFT to CBM converter.