Nookbyte Dimensional weight calculator
Enter the size and weight of your box. See its dimensional weight and the weight UPS, FedEx, USPS and DHL Express will charge you for, side by side.
Results
| Carrier | Dim weight | Actual | Billable |
|---|
Orange: the dimensional weight is higher than the actual weight, so it sets the billable weight.
Billable weight is what the rate is based on, not the price. Rules checked on 29 October 2026. Account contracts can use other divisors.
How to work out dimensional weight
- Measure the length, width and height of the packed box in inches, at the longest points.
- Round each side up to the next whole inch, so 12.2 inches becomes 13.
- Multiply the three sides to get the cubic size, then divide by the carrier's divisor.
- Round the answer up to the next whole pound. That is the dimensional weight.
- Weigh the box and round up to the next pound. The carrier bills whichever of the two is higher.
For example, an 18 × 14 × 10 inch box is 2,520 cubic inches. Divided by 139 that is 18.13, so UPS, FedEx and USPS bill it as 19 pounds, even if it weighs 6.
Divisors and rounding by carrier
| Carrier | Divisor | When it applies | Rounding | Source |
|---|---|---|---|---|
| UPS, daily rates | 139 | Every package, in the US and abroad | Each side up to the next inch, minimum 1 inch. Result up to the next pound. | UPS daily rates guide |
| UPS, retail rates | 166 in the US, 139 for exports | Every package, when you ship without daily rates (for example at The UPS Store) | Each side up to the next inch. Result up to the next pound. | UPS 2026 retail rates guide |
| FedEx Express and Ground | 139 | Every package, in the US and abroad | Each side up to the next inch. Result up to the next pound. | FedEx Service Guide 2026 |
| USPS Priority Mail, Priority Mail Express, Ground Advantage | 139 | Only boxes over 1 cubic foot (1,728 cubic inches) going to zones 1 to 9 | Each side up to the next inch. Result up to the next pound. Over 70 lb pays the 70 lb price. | USPS DMM 123 |
| DHL Express | 5,000 (cm and kg) | Every international shipment | Weight rounded up to the next half kilo. | DHL Express |
Checked on 29 October 2026. USPS rules from the Domestic Mail Manual sections 123, 133 and 604.7 (updated 12 July 2026). UPS retail rules from the 2026 UPS Rate and Service Guide for retail rates; UPS daily rates use 139 per the UPS Rate and Service Guide for daily rates. FedEx rounding from the FedEx Ground Economy 2026 guide. DHL rounding from DHL Express UK.
Questions
What is dimensional weight?
Dimensional weight, or DIM weight, is a weight that carriers work out from the size of a box. They multiply length, width and height, then divide by a number called the divisor. If the result is more than the box really weighs, you pay for the dimensional weight instead. It stops large, light parcels from travelling at the price of small heavy ones.
What divisor do UPS, FedEx and USPS use?
In inches and pounds, UPS daily rates and FedEx divide by 139. USPS also divides by 139 since its July 2026 rule change, but only for parcels larger than one cubic foot (1,728 cubic inches). UPS retail rates, which you pay without a UPS account or at The UPS Store, divide by 166 within the US and by 139 for exports.
What divisor does DHL Express use?
DHL Express works in centimetres and kilograms: length × width × height ÷ 5,000. DHL Express UK says weights are rounded up to the next half kilo.
How do carriers round the measurements?
UPS, FedEx and USPS round every measurement up to the next whole inch, so 12.1 inches counts as 13. They then round the dimensional weight up to the next whole pound. The calculator applies those steps for you and shows the rounded box size it used.
When does USPS charge dimensional weight?
Only when the box is larger than one cubic foot, which is 1,728 cubic inches after rounding each side up. Smaller boxes are priced on their actual weight. If the dimensional weight is over 70 pounds, USPS charges its 70-pound price.
How can I lower my dimensional weight?
Use the smallest box that protects the item, since every inch counts three ways. Cut down or fold tall boxes, use padded mailers for soft goods, and measure after packing, rounding up, so you are not surprised by an adjustment. For small, heavy items the actual weight usually wins anyway.
Is this the price I will pay?
No. The calculator shows the weight a carrier bills, not the price. Your rate also depends on the service, the zone or country, surcharges and any discounts on your account. Negotiated contracts can use a different divisor, so check yours if you have one.