USPS · commercial cubic
USPS Ground Advantage cubic tier finder.
Enter the outside dimensions. Get the cubic tier after USPS quarter-inch rounding, and whether the piece is eligible for cubic prices.
Package
Cubic tier
How USPS determines the cubic tier
Per DMM 283 section 1.3: measure length, width and height at each dimension's maximum point, round each down to the nearest 1/4 inch, multiply, and divide by 1,728 to get cubic feet. The piece goes in the first tier whose limit it does not exceed. Example from the DMM: 6-1/8 x 5-7/8 x 6-3/8 in rounds to 6 x 5-3/4 x 6-1/4 in = 215.6 cu in = 0.125 cu ft, so tier 0.20.
| Tier | Cubic feet | Cubic inches (up to) |
|---|---|---|
| 0.10 | up to 0.10 | 172.8 |
| 0.20 | over 0.10 to 0.20 | 345.6 |
| 0.30 | over 0.20 to 0.30 | 518.4 |
| 0.40 | over 0.30 to 0.40 | 691.2 |
| 0.50 | over 0.40 to 0.50 | 864 |
| 0.60 | over 0.50 to 0.60 | 1,036.8 |
| 0.70 | over 0.60 to 0.70 | 1,209.6 |
| 0.80 | over 0.70 to 0.80 | 1,382.4 |
| 0.90 | over 0.80 to 0.90 | 1,555.2 |
| 1.00 | over 0.90 to 1.00 | 1,728 |
The DMM lists ten tiers, 0.10 through 1.00 cubic foot.
Eligibility and soft packs
Each cubic piece must measure 1 cubic foot or less, weigh 20 pounds or less, and have a longest dimension of no more than 22 inches. Rolls and tubes are not eligible. For soft packs (poly, plastic, cloth) and padded envelopes, the tier uses the outside length plus width, each rounded down to 1/4 inch, with a 36 inch maximum: up to 21 in is tier 0.10, over 21 to 27 is 0.20, over 27 to 31 is 0.30, over 31 to 34 is 0.40, and over 34 to 36 is 0.50. Pleated or expandable pieces must use the three-dimension method.
Cubic prices apply to USPS Ground Advantage Commercial. Prices by zone are in Notice 123 (effective October 4, 2026) and are not reproduced here. Notice 123 also lists length surcharges above 22 inches and 30 inches and a volume surcharge above 2 cubic feet for parcels that are not cubic-priced; amounts differ by price list, so check the table for your service.
Sources
- USPS Domestic Mail Manual 283, USPS Ground Advantage Commercial, section 1.3 Cubic (revisions marked 7-12-26, retrieved 2026-10-18)
- USPS Notice 123, Price List, effective October 4, 2026 (retrieved 2026-10-18)
Carriers revise thresholds and fees; confirm against the live document before relying on a figure for a contract or a dispute. This is a guide, not a carrier quote or a ruling.
FAQ
What are the USPS Ground Advantage cubic tiers?
Ten tiers in 0.10 cubic foot steps from 0.10 up to 1.00 cubic foot, for pieces up to 20 pounds with a longest dimension no more than 22 inches.
How does USPS round dimensions for cubic pricing?
Each dimension is rounded down to the nearest 1/4 inch before multiplying length x width x height and dividing by 1,728. 12-3/8 inches becomes 12-1/4 inches.
How are poly mailers priced in cubic tiers?
Soft packs and padded envelopes use the outside length plus width of the packaging, each rounded down to 1/4 inch: up to 21 inches is tier 0.10 and the maximum is 36 inches, which is tier 0.50.
What if my package is over one cubic foot?
It is not eligible for cubic prices. USPS says Ground Advantage Commercial parcels over 1 cubic foot (1,728 cubic inches) are charged on the greater of actual or dimensional weight.