Dimensional Weight Calculator
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DIM weight = (L × W × H) ÷ divisor — switch US (in, lb) or metric (cm, kg). Billable weight is the greater of actual or rounded DIM weight.
Rates last reviewed: July 2026
Package dimensions & weight
Billable weight
22 lb
Billed at dimensional weight
- Dimensional weight
- 22 lb
- Actual weight
- 8 lb
- Volume
- 3,024 in³
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How dimensional weight works
Dimensional (DIM) weight estimates the "shipping weight" of a large, lightweight box by volume rather than actual scale weight — carriers introduced it because bulky, low-density packages take up truck and plane space out of proportion to what they weigh. The formula is length × width × height (in inches) divided by a divisor set by the carrier, then rounded up to the next whole pound.
US domestic carriers (UPS, FedEx, USPS Priority Mail) commonly use a divisor of 139 for ground and air shipments; international and some express air services use 166. A smaller divisor produces a larger dimensional weight, so always check which divisor applies to your specific service before estimating cost — carriers update these periodically.
Example: an 18 × 14 × 12 in box has a volume of 3,024 cubic inches. Divided by 139, that is 21.76 lb, rounded up to 22 lb of dimensional weight — even if the actual contents weigh only 8 lb, the carrier bills the higher of the two.
Billable weight is whichever is greater: actual scale weight or rounded dimensional weight. Carriers compare the two after rounding DIM up to the next whole pound (or kilogram internationally).
Right-sizing packaging is the main lever. Reducing any single dimension lowers volume and can bring billable weight back to actual scale weight — often saving more than switching carriers.
The 139 divisor is standard for UPS, FedEx, and USPS domestic services; 166 appears on many international air quotes. Always confirm the divisor on your specific service level before quoting a customer.
Metric mode converts your cm/kg inputs internally to inches and pounds for the divisor math, then displays billable weight in kilograms again for international shippers.
This is a planning estimate — carrier invoices may add fuel surcharges, residential fees, and dimensional weight minimums not modeled here.
Official sources
Rates and formulas in this calculator reference the documentation below. Confirm current numbers on the source site before relying on them. Links do not imply endorsement by those organizations of Calcometry or this tool.
Common questions
What divisor should I use — 139 or 166?
139 is the standard for most US domestic ground and air services from UPS, FedEx, and USPS. 166 typically applies to international and some express air shipments. Always confirm the exact divisor with your carrier and service level, since it can change.
Do carriers always charge dimensional weight?
No — carriers bill whichever is greater: your package's actual scale weight or its dimensional weight. Small, dense packages are usually billed at actual weight; large, light packages are billed at DIM weight.
Is dimensional weight rounded?
Yes. Most carriers round the calculated dimensional weight up to the next whole pound (or kilogram internationally) before comparing it to actual weight.
Why would I be billed more than my package actually weighs?
If your box is large relative to its weight, dimensional weight can exceed actual weight — carriers bill the higher figure. Right-sizing packaging reduces this surcharge.
How do I lower my billable weight?
Use the smallest box that safely fits your product. Reducing any dimension lowers dimensional weight and can bring billable weight back to actual scale weight.