Dimensional weight calculator
Dimensional weight is the weight a parcel carrier bills for a package’s size: length × width × height in inches, divided by a divisor. UPS Daily Rates and FedEx divide by 139, UPS Retail Rates by 166, and USPS by 139 for Priority Mail and Ground Advantage Commercial packages over one cubic foot since July 12, 2026. The carrier bills the greater of dimensional and actual weight.
Updated October 12, 2026
Divisors and rules from UPS, FedEx and USPS published guidance, checked October 2026. Contract rates can use a different divisor; your agreement wins.
How to calculate dimensional weight
Measure length, width and height in inches at the longest points. UPS and USPS round each side up to the next whole inch, so 16.2 inches counts as 17.
Multiply the three sides to get cubic inches.
Divide by the carrier’s divisor and round up to the next whole pound.
Round the scale weight up to the next whole pound too.
Bill the greater of the two. That is the billable weight.
Divisors by carrier
| Carrier and rate | Divisor | When it applies |
|---|---|---|
| UPS, Daily Rates | 139 | All packages |
| UPS, Retail Rates | 166 | All packages |
| FedEx | 139 | U.S., Puerto Rico and international |
| USPS Priority Mail, retail and commercial | 139 | Over 1,728 cubic inches |
| USPS Ground Advantage Commercial | 139 | Over 1,728 cubic inches |
Sources: UPS, FedEx and USPS pages listed at the bottom, checked October 12, 2026. A contract can name its own divisor; if yours does, pick Custom divisor in the calculator.
Recent rule changes
USPS moved from 166 to 139 on July 12, 2026. The Domestic Mail Manual now says to round each side up to the whole inch and, if the result is over 1,728 cubic inches, divide by 139 and round up. Packages of one cubic foot or less are still billed by actual weight, and dimensional weight above 70 pounds is charged at the 70-pound price.
UPS rounds each side up. UPS’s measuring guide says to round up to the next whole number, so 1.01 to 1.99 inches counts as 2.
FedEx publishes 139 for U.S., Puerto Rico and international shipments. Its dimensional weight page still says to round each side to the nearest whole inch, so check the current FedEx Service Guide, which governs billing. Leave “Round each side up” ticked for the stricter answer.
Worked examples
A 16.2 × 12 × 10 inch box weighing 4 pounds
Rounded up, the box is 17 × 12 × 10 inches, or 2,040 cubic inches. On UPS Daily Rates, 2,040 ÷ 139 = 14.68, so the dimensional weight is 15 pounds and the billable weight is 15 pounds, not 4. On UPS Retail Rates, 2,040 ÷ 166 = 12.29, so 13 pounds. USPS bills 15 pounds too, because 2,040 cubic inches is over the 1,728 threshold.
A 10 × 8 × 6 inch box weighing 2.3 pounds
The box is 480 cubic inches. USPS does not apply dimensional weight under one cubic foot, so it bills the actual weight rounded up: 3 pounds. On UPS Daily Rates, 480 ÷ 139 = 3.45, so the dimensional weight is 4 pounds and the billable weight is 4.
How to lower dimensional weight
Use the smallest carton that protects the product. One extra inch on a box with a 12 × 12 inch face adds 144 cubic inches.
Watch fractions. With sides rounded up, a 12.1 inch side bills as 13.
For USPS, a package of 1,728 cubic inches or less is billed by actual weight.
Ship heavy, compact items by parcel and bulky pallets by LTL, where the freight class and density set the price instead.
Frequently asked questions
What is a DIM divisor?
The divisor, or DIM factor, turns cubic inches into pounds. A lower divisor gives a higher dimensional weight. UPS calls it the DIM factor and publishes 139 for Daily Rates and 166 for Retail Rates.
Does USPS charge dimensional weight on small boxes?
No. USPS applies dimensional weight to Priority Mail and Ground Advantage Commercial parcels only when they exceed one cubic foot, which is 1,728 cubic inches.
Should I use 139 or 166?
It depends on the carrier and the rate. UPS uses 139 on Daily Rates and 166 on Retail Rates. FedEx uses 139. USPS uses 139 for Priority Mail and Ground Advantage Commercial packages over one cubic foot since July 12, 2026. If your agreement names a different number, that number applies.
Can I enter centimeters and kilograms?
Yes. Switch the units at the top of the calculator. It converts to inches and pounds and applies the U.S. carriers’ published rules, then shows the billable weight in pounds and kilograms.
Is dimensional weight the same as freight class?
No. Dimensional weight is how parcel carriers bill boxes. LTL freight on pallets is priced by freight class, which for many items follows density. Use the freight class calculator for pallets.
Related calculators
Freight class calculator: for pallets and crates moving LTL.
Pallet calculator: how many of these boxes fit on a pallet.
Sources
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