Dimensional Weight Calculator
A 40 x 30 x 50 cm box weighing 8 kg has a dimensional weight of 12 kg (60,000 ÷ 5,000), so DHL bills 12 kg. A 16 x 12 x 10 in box at 6 lb is billed 14 lb by UPS in the US (1,920 ÷ 139 = 13.8, rounded up).
How to use
- Pick a carrier and choose centimetres and kilograms or inches and pounds for your box.
- Enter length, width, height, weight and quantity. Use Add box for a shipment with different sizes.
- Read the billable weight, which is the larger of the actual and dimensional weight after the carrier's rounding. The working for each box is listed.
How it works
Dimensional weight = length × width × height ÷ divisor. International express services (DHL Express, FedEx, UPS) use 5,000 cm³ per kg. US domestic FedEx, UPS and USPS Priority Mail use 139 in³ per lb.
Billable weight = the larger of actual weight and dimensional weight, then rounded up: to the next 0.5 kg internationally and to the next whole pound in the US. Carriers charge per package, so each box is rounded before adding.
FedEx and UPS round each dimension to the nearest whole inch for US shipments. USPS rounds each dimension up to a whole inch and applies dimensional weight only to parcels over 1,728 in³ (1 cubic foot). Rules differ by service and contract, so check your carrier's current terms.
Divisors used here
| Carrier | Divisor | Rounding used |
|---|---|---|
| DHL Express | 5,000 cm³/kg | Up to next 0.5 kg |
| FedEx International | 5,000 cm³/kg | Up to next 0.5 kg |
| UPS International | 5,000 cm³/kg | Up to next 0.5 kg |
| FedEx US domestic | 139 in³/lb | Dimensions to nearest inch, weight up to next lb |
| UPS US domestic | 139 in³/lb | Dimensions to nearest inch, weight up to next lb |
| USPS Priority Mail | 139 in³/lb | Dimensions up, over 1,728 in³ only, weight up to next lb |
Notes and limits
- USPS Priority Mail used 166 in³/lb in the past. The current USPS Domestic Mail Manual 123 text uses 139 for parcels over 1 cubic foot, so older tables that show 166 are out of date.
- The 0.5 kg step is the common express increment. Heavier parcels, freight and contract rates can use other steps or divisors. Use the custom divisor for those.
- This is an estimate of the weight used for pricing, not a quote. Surcharges for size, weight or non-rectangular parcels are not included.
Sources: DHL · FedEx · UPS · USPS DMM 123Last reviewed 2026-10-16
FAQ
What is dimensional weight?
A size-based weight carriers use for light but bulky parcels. It is length × width × height divided by a carrier divisor, and you are billed on the larger of that and the actual weight.
How do I calculate volumetric weight in kg?
Multiply length × width × height in centimetres and divide by 5,000. A 40 × 30 × 50 cm box is 60,000 ÷ 5,000 = 12 kg.
How do I calculate dimensional weight in pounds?
Multiply length × width × height in inches and divide by 139 for FedEx, UPS and USPS domestic shipments. A 16 × 12 × 10 in box is 1,920 ÷ 139 = 13.8, billed as 14 lb.
Which carrier divisor should I use?
Use the one on your carrier agreement. Standard published divisors are 5,000 cm³/kg for international express and 139 in³/lb for US domestic. A lower divisor means a higher dimensional weight.
How do I reduce dimensional weight?
Use the smallest box that protects the goods, remove void fill, and avoid oversize cartons for light items. Cutting each side by 1 cm can lower the billable weight noticeably.
How are several boxes billed?
Each package is rated on its own, so the tool computes and rounds every box and then adds them. Totals for the dimensional weight shown are unrounded sums.