3,888 cubic inches (2.25 cu ft, 0.0637 m³). Often used for bedding, bulky soft goods.
Billable weight floor by carrier
Packed lighter than this, you are billed this weight anyway.
| Carrier | Divisor | DIM weight |
|---|
| USPS | 139 | 28 lb |
| UPS (Daily Rates) | 139 | 28 lb |
| FedEx | 139 | 28 lb |
| UPS (Retail Rates) | 166 | 24 lb |
| DHL Express (International) | 5000 | 13 kg |
Stepping down to a 24 × 12 × 12 in box drops the UPS and FedEx floor to 25 lb, 3 lb less per parcel.
This box is over 1 cubic foot, so USPS applies dimensional weight.
Try it with your packed weight
2Your resultlive
D
Priority Mail, Priority Mail Express, Ground Advantage, Parcel Select
Billed on dimensions
A box 1 inch smaller on every side bills 5 lb less.
What is the dimensional weight of a 18x18x12 box?
3,888 cubic inches ÷ 139 = 27.97, rounded up to 28 lb for UPS Daily Rates and FedEx. USPS also bills 28 lb since the July 2026 change.
How heavy does a 18x18x12 box need to be to avoid DIM charges?
With UPS and FedEx, anything packed under 28 lb is billed as 28 lb. Above that, you pay actual weight.
Carrier rules verified 2026-09-30. Methodology