FedEx Dimensional (DIM) Weight is a pricing method that charges based on package volume instead of actual weight when the package takes up a lot of space relative to its weight.
FedEx DIM weight formula
As of 2026, FedEx uses a standard divisor of 139 for most shipments.
DIM weight (lbs) = (Length × Width × Height in inches) / 139
- Use inches for dimensions.
- Divide by 139 (FedEx dimensional divisor).
- Round up to the nearest whole pound.
Important notes:
- The divisor 139 (lbs/in³) or 5,000 (kg/cm³) applies to most U.S. domestic and international shipments, but it can vary depending on contract terms.
- If your package’s DIM weight is greater than the actual weight, you’ll be charged based on the DIM weight.
- Measure at the longest points, including bulges.
- Each dimension is typically rounded to the nearest whole inch before calculating.