What is USPS cubic pricing?

A commercial price structure where the postage depends on the package's volume tier and the zone, not its weight. Dense, small, heavy items — books, hardware, cosmetics, jars — are often far cheaper at cubic prices than at weight-based prices.

Who can use cubic prices?

Cubic prices are commercial prices. You get them through shipping software and postage platforms that offer USPS commercial pricing, not at the retail counter.

Ground Advantage cubic takes packages up to 1 cubic foot; Priority Mail cubic stops at 0.5 cubic foot. Both require 20 lb or less and no side longer than 22 inches, and neither accepts rolls or tubes. Soft packs are measured by length plus width instead of volume, up to 36 inches combined.

How does the rounding work?

USPS measures each dimension and rounds it down to the nearest quarter inch before multiplying. A 10.9 inch side counts as 10.75. Rounding down can drop a package into a cheaper tier, which is why measuring precisely matters.

How do the tiers work?

Tiers run in 0.1 cubic-foot steps: five tiers up to 0.5 for Priority Mail, ten up to 1.0 for Ground Advantage. The tier is the first step at or above your rounded volume, and the top of each band is inclusive, so exactly 0.20 is still tier 0.2 while 0.201 is tier 0.3. Prices rise with the tier and the zone.

USPS Cubic Pricing Calculator

Check whether a box or soft pack qualifies for USPS cubic pricing and get its tier, with each side rounded down to the quarter inch exactly as the Domestic Mail Manual says. Prices are set by tier and zone, so the tier is the number you need.

Rates verified Nov 6, 2026Source: USPS DMM 283.1.3 — Ground Advantage Commercial cubic pricing

Package

Service

Zone

From the USPS zone chart for your origin ZIP

Packaging

Weight

Length

Width

Height

Cubic tier and price

Tier

0.3

Zone 4 commercial price

$9.63

Rounded down to the quarter inch: 10 × 8 × 6 = 480.00 in³ ÷ 1,728 = 0.278 cubic feet, which is tier 0.3.

Price from USPS Notice 123 effective 4 Oct 2026, USPS Ground Advantage — Commercial, Cubic. Cubic prices are set by tier and zone, not weight; surcharges for unmanifested pieces, hazardous materials or special contents are extra.

How the cubic tier is determined

Measure length, width and height to the quarter inch and round each one down.
Multiply the three rounded sides and divide by 1,728 to get cubic feet.
The tier is the next 0.1 step at or above that volume: up to 0.5 for Priority Mail, up to 1.0 for Ground Advantage.
Soft packs skip the volume maths: add the rounded length and width and read the tier from the length-plus-width bands.

Soft pack tiers

Length + width (inches)	Tier
up to 21	0.1
up to 27	0.2
up to 31	0.3
up to 34	0.4
up to 36	0.5

USPS’s own example, reproduced

The Domestic Mail Manual gives this case: a box measuring 6⅛ × 5⅞ × 6⅜ inches rounds down to 6 × 5¾ × 6¼, which is 215.6 cubic inches, or 0.125 cubic feet, so it is tier 0.2. Type 6.125, 5.875 and 6.375 into the calculator and it prints tier 0.2 and, for zone 4, the Priority Mail cubic price of $11.19 or the Ground Advantage price of $8.74. That example is one of the automated tests behind this page.

A second example

A 10 × 8 × 6 inch box weighing 3 lb: 480 cubic inches ÷ 1,728 = 0.278 cubic feet, tier 0.3. A 10.9 × 8.2 × 6.1 box first rounds down to 10.75 × 8 × 6 = 516 cubic inches = 0.299 cubic feet, still tier 0.3. Make it 10.9 × 8.2 × 6.3 and the rounded 6.25 pushes it to 537.5 cubic inches = 0.311, which is tier 0.4.

Current commercial cubic prices (Notice 123, effective 4 October 2026)

Ground Advantage — Commercial, cubic, USD per piece:

Tier	Z1	Z2	Z3	Z4	Z5	Z6	Z7	Z8	Z9
0.1	7.85	7.91	8.23	8.39	9.04	9.76	10.08	10.68	10.68
0.2	8.22	8.29	8.54	8.74	9.92	11.21	11.60	12.39	12.39
0.3	8.79	8.85	9.21	9.63	11.51	13.38	14.03	15.22	15.22
0.4	9.72	9.78	10.16	10.99	13.48	15.71	16.66	18.34	18.34
0.5	10.24	10.31	10.68	11.58	14.37	16.75	17.94	19.95	19.95
0.6	10.49	10.55	10.96	12.08	15.15	17.73	19.10	21.41	21.41
0.7	10.59	10.65	11.21	12.47	15.81	18.52	20.07	22.62	22.62
0.8	10.73	10.88	11.99	12.99	16.44	19.27	20.99	23.76	23.76
0.9	11.49	11.73	12.89	14.09	17.06	20.04	21.89	24.94	24.94
1.0	13.07	13.39	14.33	15.59	18.68	21.86	23.93	27.35	27.35

Priority Mail — Commercial, cubic, USD per piece:

Tier	Z1	Z2	Z3	Z4	Z5	Z6	Z7	Z8	Z9
0.1	9.46	9.74	10.13	10.90	13.87	15.54	16.24	16.36	33.94
0.2	9.50	9.79	10.18	11.19	14.02	16.19	17.16	17.22	35.79
0.3	9.85	10.11	11.15	13.08	17.41	19.71	21.36	21.42	44.76
0.4	11.71	11.94	13.28	15.77	21.98	26.63	29.00	29.05	60.03
0.5	12.24	12.35	13.88	16.75	24.06	29.02	31.99	32.31	66.98

When cubic beats weight-based pricing

Cubic pricing wins when the item is heavy for its size: in the smaller tiers, a 15 lb package often ships for the price of a 2 lb package. It loses on large, light items because the tier climbs with the box, not the contents. Compare both before buying the label.

Questions sellers ask

What is USPS cubic pricing?: A commercial price structure where the postage depends on the package's volume tier and the zone, not its weight. Dense, small, heavy items — books, hardware, cosmetics, jars — are often far cheaper at cubic prices than at weight-based prices.
Who can use cubic prices?: Cubic prices are commercial prices. You get them through shipping software and postage platforms that offer USPS commercial pricing, not at the retail counter.
What are the limits?: Ground Advantage cubic takes packages up to 1 cubic foot; Priority Mail cubic stops at 0.5 cubic foot. Both require 20 lb or less and no side longer than 22 inches, and neither accepts rolls or tubes. Soft packs are measured by length plus width instead of volume, up to 36 inches combined.
How does the rounding work?: USPS measures each dimension and rounds it down to the nearest quarter inch before multiplying. A 10.9 inch side counts as 10.75. Rounding down can drop a package into a cheaper tier, which is why measuring precisely matters.
How do the tiers work?: Tiers run in 0.1 cubic-foot steps: five tiers up to 0.5 for Priority Mail, ten up to 1.0 for Ground Advantage. The tier is the first step at or above your rounded volume, and the top of each band is inclusive, so exactly 0.20 is still tier 0.2 while 0.201 is tier 0.3. Prices rise with the tier and the zone.

Related calculators

Sources and verification dates

USPS DMM 283.1.3 — Ground Advantage Commercial cubic pricing — checked Nov 6, 2026, in effect since Jul 12, 2026
USPS DMM 223.1.3 — Priority Mail Commercial cubic pricing — checked Nov 6, 2026, in effect since Jul 12, 2026
USPS Notice 123 — Price List (cubic price tables) — checked Nov 6, 2026, in effect since Oct 4, 2026

Every value on this page is read from the linked official pages on the date shown. If a platform changes a fee, the change log records the old and new values and the effective date.