The basic dimensional weight formula
DIM weight = length × width × height ÷ DIM divisorUse one measurement system consistently. Inch/pound calculations commonly use divisors such as 139 or 166. Centimeter/kilogram calculations commonly use 5000 or 6000.
What the divisor changes
| Divisor | Typical units | For the same box |
|---|---|---|
| 139 | inches / pounds | Higher DIM result than 166 |
| 166 | inches / pounds | Lower DIM result than 139 |
| 5000 | centimeters / kilograms | Higher DIM result than 6000 |
| 6000 | centimeters / kilograms | Lower DIM result than 5000 |
Worked examples
20 × 16 × 12 inches
Volume = 3,840 in³. Using 139: 3,840 ÷ 139 = 27.63 lb before service-specific rounding. Using 166: 3,840 ÷ 166 = 23.13 lb.
60 × 40 × 35 centimeters
Volume = 84,000 cm³. Using 5000: 84,000 ÷ 5000 = 16.8 kg. Using 6000: 84,000 ÷ 6000 = 14.0 kg.
Current carrier examples
FedEx: its U.S. dimensional-weight page states to multiply package dimensions in inches and divide by 139 for U.S., Puerto Rico and international shipments. FedEx source.
UPS: UPS currently states the divisor varies by rate type: 139 for Daily Rates and 166 for Retail Rates. UPS source.
USPS: current Postal Explorer rules state that applicable low-density parcels exceeding 1,728 cubic inches use a 139 divisor after required measurement rules, with service-specific eligibility. USPS source.
DHL Express: DHL publishes a standard volumetric divisor of 5000 for cm/kg or 139 for in/lb. DHL source.
DIM weight is not always the final invoice weight
Carriers may round dimensions or calculated weights, apply size thresholds, minimum billable weights, surcharges, rate-type rules or contract terms. Use this formula to understand the comparison, then verify the exact service.
Frequently asked questions
Why does a smaller divisor create a larger DIM weight?
Because the same package volume is divided by a smaller number. For example, 3,840 ÷ 139 is larger than 3,840 ÷ 166.
Is 5000 exactly the same as 139?
They are commonly used in different unit systems and are close equivalents, but use the factor published for the exact service rather than converting one rule into another.
Should I round before or after calculating?
Follow the carrier's rule. Some carriers require measurements to be rounded before multiplication and the calculated weight to be rounded afterward.