When determining shipping costs, carriers use a concept known as Billable Weight. This calculation ensures that the space a package occupies in a vehicle is accounted for, alongside its physical weight.
Important: Carriers always round up to the next whole pound (e.g., 1.01 lbs = 2 lbs).
Billable Weight Formula:
The billable weight is always the greater of the two values:
Billable Weight = Max(Actual Weight, DIM Weight)
DIM Divisors and Formulas (2026)
To calculate DIM weight, use the following formula:
DIM weight = (Length x Width x Height) / DIM Divisor
Atomix Service DIM Divisors
Service Level | DIM Divisor |
Economy | 166 |
Ground | 166 |
Expedited | 194 |
International | 139 |
Standard Carrier DIM Divisors
UPS Ground Services: 139
FedEx Ground Services: 139
How Specific Carriers Calculate Weight
UPS and FedEx
Both use the greater of actual weight or DIM weight.
The DIM divisor applied depends on the specific carrier service level selected.
USPS
USPS exclusively uses actual weight for its pricing structure (no DIM weight calculation applied).
Calculation Example
If you ship an international package in a 10x10x10 inch box:
Calculate volume: 10 * 10 * 10 = 1,000.
Apply international divisor: 1,000 / 139 = 7.19 lbs.
Billable Weight: 8 lbs (due to rounding up to the next whole pound).