Billable Weight
19 lbs
DIM Weight
18.1 lbs
Actual
8.0 lbs
Carrier bills the higher DIM weight. Use a smaller box to reduce DIM weight.
| Carrier | DIM Divisor | DIM Weight | Billable | Billed By |
|---|---|---|---|---|
| UPS | 139 | 18.1 lbs | 19 lbs | DIM |
| FedEx | 139 | 18.1 lbs | 19 lbs | DIM |
| USPS | 166 | 15.2 lbs | 16 lbs | DIM |
| DHL | 139 | 18.1 lbs | 19 lbs | DIM |
| Carrier | Domestic (in³) | Metric (cm³) | Notes |
|---|---|---|---|
| UPS | 139 | 5,000 | Same for domestic & intl |
| FedEx | 139 | 5,000 | Same for domestic & intl |
| USPS | 166 | 6,000 | More generous divisor |
| DHL | 139 | 5,000 | International focus |
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Result
An 18×14×10″ box has a DIM weight of 18.1 lbs at UPS, which is higher than the 8 lb actual weight. UPS bills 19 lbs (rounded up).
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Result
A dense 15 lb package in a small box has a DIM weight of only 4.3 lbs. USPS bills the actual weight since it's higher — DIM weight doesn't affect dense packages.
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Result
A large 24×18×18″ box with only 5 lbs inside has a DIM weight of 55.9 lbs at FedEx. You'd be billed for 56 lbs — over 11× the actual weight.
Dimensional weight (DIM weight) is a pricing technique that reflects the amount of space a package occupies compared to its actual weight. It is calculated by multiplying length × width × height and dividing by a carrier-specific DIM divisor (typically 139 for inches or 5,000 for centimeters).
| Carrier | DIM Divisor (in³) | DIM Divisor (cm³) | Notes |
|---|---|---|---|
| UPS | 139 | 5,000 | Same domestic & intl |
| FedEx | 139 | 5,000 | Same domestic & intl |
| USPS | 166 | 6,000 | Most generous |
| DHL | 139 | 5,000 | International focus |
Carriers use DIM weight because a large, lightweight box takes up the same truck space as a heavy one. If every package were priced by actual weight alone, carriers would lose money on bulky shipments because their trucks would fill up before reaching capacity by weight.
The most effective strategy is right-sizing your box. Every extra inch of empty space increases the DIM weight. Using the smallest possible box, switching to poly mailers for soft goods, and comparing USPS (which has a more generous 166 divisor) can all reduce costs significantly.
USPS has the most favorable DIM weight calculation with a divisor of 166 versus 139 for UPS, FedEx, and DHL. This means USPS calculates a lower DIM weight for the same size box. Additionally, USPS Priority Mail flat-rate boxes completely ignore dimensional weight.
| Box Size | UPS/FedEx DIM | USPS DIM | Savings |
|---|---|---|---|
| 12×10×6″ | 5.2 lbs | 4.3 lbs | 0.9 lbs |
| 18×14×10″ | 18.1 lbs | 15.2 lbs | 2.9 lbs |
| 24×18×18″ | 55.9 lbs | 46.8 lbs | 9.1 lbs |
Most carriers apply DIM weight pricing to all packages, but there are exceptions. USPS Priority Mail flat-rate boxes are exempt. UPS and FedEx both apply DIM to all Ground and Express packages. Small packages under certain thresholds may also be exempt depending on the carrier and your negotiated rates.
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Last Updated: Mar 9, 2026
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.