Quick answer: Dimensional weight (DIM weight) = Length × Width × Height ÷ DIM factor. In inches and pounds, FedEx and UPS use a factor of 139 and USPS uses 166; for air cargo IATA uses L×W×H in cm ÷ 6,000. The carrier bills the higher of actual weight and dimensional weight, called the billable or chargeable weight.
Dimensional weight (DIM weight) is a pricing method used by carriers to charge for the space a package occupies — not just its actual weight. If a large, lightweight box costs more to transport by volume than by mass, the carrier bills you for the dimensional weight instead.
Most carriers apply dimensional weight pricing to both domestic and international shipments. Understanding how to calculate it is the first step to controlling shipping costs.
The standard formula is:
Dimensional Weight = (Length × Width × Height) ÷ DIM Factor
Where dimensions are in inches or centimeters and the DIM factor varies by carrier and service type.
| Carrier / Mode | DIM Factor (inches) | DIM Factor (cm) |
|---|---|---|
| UPS / FedEx domestic | 139 | 5,000 |
| USPS domestic | 166 | 6,000 |
| Air freight (IATA) | 166 | 6,000 |
| LTL freight | 125–194 (varies) | Varies |
A package measuring 20" × 16" × 12" with an actual weight of 5 lbs:
Without accurate dimension capture, you either overbill customers or absorb the loss on every one of those shipments.
When warehouse staff measure packages manually, common errors include:
Manual dimension capture has error rates of 3–8%, which directly translates to underbilled dimensional weight and lost revenue.
An automated dimensioning system captures length, width, and height in under one second — accurately to ±2mm — and pushes the data directly to your WMS, TMS, or billing system. No manual input, no rounding errors, no disputes.
For a courier processing 5,000 parcels per day, recovering even 2% of underbilled DIM weight can mean tens of thousands of dollars per month in recaptured revenue.
Dim weight (dimensional weight) is a pricing weight that reflects how much space a package occupies. Carriers calculate it from the package's dimensions and bill whichever is greater: the actual scale weight or the dim weight.
Measure length, width and height in inches, rounding each to the nearest whole inch, multiply them to get cubic inches, and divide by the carrier's DIM factor (139 for FedEx and UPS, 166 for USPS). Round the result up to the next whole pound.
IATA uses 6,000 cm³ per kg (1:6000). Many express carriers such as DHL Express use 5,000 cm³ per kg. Divide L×W×H in centimeters by the factor to get volumetric weight in kilograms.
Yes. Our free calculator computes dimensional and billable weight for FedEx, UPS, DHL, USPS and IATA air cargo in one step, with worked examples.
The biggest source of DIM errors is manual measurement and declared data. An automated dimensioner measures every package in about a second, applies the correct factor and stores photo evidence, which removes disputes and recovers under-billed revenue.
Last updated: September 30, 2026. Specifications reflect current CubiQ product data.
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