USPS is the friendliest US carrier for DIM weight in two important ways: a higher divisor (166 vs 139 for FedEx/UPS) and a minimum-volume rule that exempts packages under 1 cubic foot from DIM pricing entirely. Flat Rate boxes are also exempt regardless of size.
Awaiting dimensions. Enter package details to compute billable weight.
| Service | Imperial (in/lb) | Metric (cm/kg) | Notes |
|---|---|---|---|
| Ground Advantage | 166 | 6000 | Only > 1 ft³ |
| Priority Mail | 166 | 6000 | Only > 1 ft³ · Flat Rate exempt |
| Priority Mail Express | 166 | 6000 | Only > 1 ft³ · Flat Rate exempt |
| First Class Package | N/A | N/A | DIM does not apply |
Small or heavy dense packages, Flat Rate boxes, light-volume shippers
Large lightweight bulky items above 1 ft³ (DIM weight still applies)
Run an actual rate quote on USPS's official site to confirm pricing and check current surcharges.
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USPS uses a divisor of 6000 cm³/kg (metric) or **166 in³/lb** (imperial). The DIM weight formula is volume divided by this number, rounded up to the nearest whole pound or kilogram.
USPS applies dimensional weight to packages above 1,728 in³ (1 ft³). The billable weight is always the greater of the actual weight or the calculated DIM weight.
Use right-sized packaging — every cubic inch you save is divided by the divisor and removed from your billable weight. Avoid excessive void fill and consider custom box sizes for products you ship frequently. For occasional shippers, use the calculator above to test packaging changes before you commit to new materials.