Dimensional weight calculator
Dimensional weight is the weight a carrier bills for a box’s size: length × width × height in inches, divided by a divisor such as 139. You pay for whichever is greater, the dimensional weight or the actual weight.
19 lb
billed by UPS Daily Rates
13 lb of that is empty space you pay for.
One inch off the 18-inch side saves 1 lb at UPS Daily Rates.
How dimensional weight is calculated
- Measure the box’s length, width and height and round each up to the next whole inch.
- Multiply them to get cubic inches.
- Divide by the carrier’s divisor and round up to the next pound.
- Compare with the actual weight, rounded up. The carrier bills the greater of the two.
18 × 14 × 10 = 2,520 cubic inches ÷ 139 = 18.13, so 19 lb
2026 carrier rules
| Carrier and service | Divisor | Applies to | Rounding |
|---|---|---|---|
| UPS Daily Rates | 139 | Every package | Each side up to the next whole inch; result up to the next pound |
| UPS Retail Rates | 166 | Every package | Each side up to the next whole inch; result up to the next pound |
| FedEx | 139 | Every package | Result up to the next pound; check the FedEx Service Guide for side rounding |
| USPS Priority Mail, Ground Advantage, Parcel Select | 139 since July 12, 2026 (was 166) | Only parcels over 1 cubic foot (1,728 cubic inches) | Each side up to the next whole inch; result up to the next pound; Ground Advantage caps at the 70 lb price |
Negotiated contracts can use a different divisor. The calculator rounds every side up to the next whole inch, so its numbers are the conservative case.
Questions about dimensional weight
What is dimensional weight?
Dimensional weight, or DIM weight, is a billing weight based on a package’s size. Carriers multiply the length, width and height in inches, divide by a divisor and compare the result with the actual weight. The greater of the two is the billable weight.
What DIM divisor do UPS, FedEx and USPS use in 2026?
UPS uses 139 for Daily Rates and 166 for Retail Rates. FedEx uses 139. USPS changed its divisor from 166 to 139 on July 12, 2026, for Priority Mail Express, Priority Mail, USPS Ground Advantage and Parcel Select.
Does USPS charge dimensional weight on small boxes?
No. USPS applies dimensional weight only to parcels larger than one cubic foot (1,728 cubic inches). Smaller parcels are priced on actual weight.
How can I lower my dimensional weight?
Use the smallest box that protects the product, cut empty space before you cut weight, and check the longest side first: one inch less on the longest side often drops a full billable pound. Soft goods can often ship in poly mailers instead of boxes.
Sources
- USPS Domestic Mail Manual 283, USPS Ground Advantage dimensional weight (7-12-26)
- USPS Price List Notice 123, effective July 12, 2026
- UPS, Shipping Dimensions and Weight
- FedEx, What is Dimensional Weight?
Rules checked 2026-10-27. Shipping distance changes the price too: see the shipping zone map.
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