Cubic Pricing
Cubic pricing is a USPS pricing method for Priority Mail and Ground Advantage packages up to 0.5 cubic feet and 20 pounds that charges by package volume tier and zone instead of weight.
Why it matters for ecommerce brands
Cubic pricing can make small, heavy packages much cheaper to ship with USPS, because it prices by box size and zone instead of weight. It suits dense products such as supplements, cosmetics, tools, and parts. It only applies to packages up to 0.5 cubic feet and 20 pounds. For example, a 10 × 8 × 4 inch box is 0.185 cubic feet and prices in the 0.2 tier. A 4 pound item in that box may cost less than the weight-based rate, depending on zone, so compare both rates on every shipment.
Formula and calculator
Cubic feet = (L x W x H) / 1,728
The result is rounded up to the next 0.1 cubic foot pricing tier.
Common questions
- How is USPS cubic tier calculated?
- Multiply length, width, and height in inches after rounding each down to the nearest quarter inch, then divide by 1,728 to get cubic feet. The result is rounded up to the next tier in 0.1 cubic foot steps.
- Who can use USPS cubic pricing?
- Cubic pricing is a commercial rate, available through online shipping platforms and USPS commercial accounts rather than at the retail counter. Most multi-carrier shipping software can rate it automatically.
- Is cubic pricing always cheaper than weight-based pricing?
- No. It pays off for small, dense packages. Light items in a box near 0.5 cubic feet often cost less at weight-based rates, so let your shipping software compare both.
Cite this entry
"Cubic Pricing." Fulfillment Lexicon, last reviewed October 16, 2026. https://fulfillment.wiki/glossary/cubic-pricing/