USPS Cubic Tier Pricing – Full Rate Table
USPS Cubic pricing assigns a flat rate based on your package’s cubic volume tier and shipping zone. Once your package qualifies, weight does not affect the rate a 2 lb item and an 18 lb item in the same tier pay the same postage.
The tier system has two versions: Priority Mail Cubic with 5 tiers up to 0.5 cubic feet, and Ground Advantage Cubic with 10 tiers up to 1.0 cubic feet. Most rate tables published online show only Priority Mail. This article covers both.
How Cubic Tiers Work – Two Rules Most Sellers Get Wrong
Before the rate table, two rules that affect which tier your package lands in.
Rule 1: Measure DOWN, round to nearest 0.25 inch.
When calculating cubic volume for USPS purposes, round each dimension DOWN to the nearest quarter inch before running the formula. A dimension of 11.9 inches is measured as 11.75 inches. A dimension of 8.3 inches is measured as 8.25 inches. This is the opposite of UPS and FedEx ceiling rounding.
Cubic Feet = (Length × Width × Height) ÷ 1,728
Always use the rounded-down dimensions in that formula.
Rule 2: Tier rounds UP to the next tier.
Once you have your cubic volume, the tier is determined by rounding UP to the next tier boundary. A package calculating to 0.21 cubic feet falls into the 0.3 tier not the 0.2 tier. A package at exactly 0.20 cubic feet falls into the 0.2 tier.
The tier boundaries are:
- Tier 0.1: up to and including 0.10 cubic feet
- Tier 0.2: over 0.10 up to and including 0.20 cubic feet
- Tier 0.3: over 0.20 up to and including 0.30 cubic feet
- Tier 0.4: over 0.30 up to and including 0.40 cubic feet
- Tier 0.5: over 0.40 up to and including 0.50 cubic feet
Ground Advantage Cubic adds tiers 0.6 through 1.0 using the same boundary logic.
Priority Mail Cubic Rate Table – 5 Tiers by Zone
You've read the theory—now see the actual math for your packages. Use our Carrier Savings Engine to see if you can unlock hidden USPS Cubic rates by shrinking your packaging.
Check My Savings →Priority Mail Cubic delivers in 1-3 business days. Maximum volume 0.5 cubic feet. Maximum longest side 18 inches. Maximum weight 20 lbs.
Commercial rates (approximate):
| Tier | Volume | Zone 1-2 | Zone 3 | Zone 4 | Zone 5 | Zone 6 | Zone 7 | Zone 8 |
|---|---|---|---|---|---|---|---|---|
| 0.1 | ≤ 0.10 cu ft | $8.10 | $8.35 | $8.60 | $8.95 | $9.45 | $9.80 | $10.20 |
| 0.2 | ≤ 0.20 cu ft | $8.55 | $8.80 | $9.10 | $9.50 | $10.05 | $10.45 | $10.90 |
| 0.3 | ≤ 0.30 cu ft | $9.20 | $9.55 | $9.90 | $10.35 | $10.95 | $11.40 | $11.90 |
| 0.4 | ≤ 0.40 cu ft | $10.50 | $10.90 | $11.35 | $11.85 | $12.55 | $13.05 | $13.65 |
| 0.5 | ≤ 0.50 cu ft | $11.80 | $12.25 | $12.75 | $13.35 | $14.10 | $14.70 | $15.35 |
Rates are commercial estimates. Verify current rates at Pirate Ship or Shippo before purchasing labels. See changelog.
Box dimensions that hit each Priority Mail Cubic tier:
| Tier | Example Box | Cubic Inches | Cubic Feet |
|---|---|---|---|
| 0.1 | 6 × 5 × 5 in | 150 | 0.087 |
| 0.2 | 8 × 6 × 6 in | 288 | 0.167 |
| 0.3 | 9 × 7 × 6 in | 378 | 0.219 |
| 0.4 | 10 × 8 × 6 in | 480 | 0.278 |
| 0.5 | 12 × 10 × 6 in | 720 | 0.417 |
These are examples. Any combination of dimensions producing the same cubic volume lands in the same tier. The USPS Cubic Calculator calculates your exact tier from your dimensions.
Ground Advantage Cubic Rate Table – 10 Tiers by Zone
Ground Advantage Cubic delivers in 2-5 business days. Maximum volume 1.0 cubic feet. Maximum longest side 18 inches. Maximum weight 20 lbs.
Commercial rates (approximate):
| Tier | Volume | Zone 1-2 | Zone 3 | Zone 4 | Zone 5 | Zone 6 | Zone 7 | Zone 8 |
|---|---|---|---|---|---|---|---|---|
| 0.1 | ≤ 0.10 cu ft | $7.20 | $7.45 | $7.70 | $8.10 | $8.55 | $8.90 | $9.30 |
| 0.2 | ≤ 0.20 cu ft | $7.65 | $7.90 | $8.20 | $8.65 | $9.15 | $9.55 | $9.95 |
| 0.3 | ≤ 0.30 cu ft | $8.10 | $8.40 | $8.75 | $9.20 | $9.75 | $10.15 | $10.60 |
| 0.4 | ≤ 0.40 cu ft | $9.30 | $9.65 | $10.05 | $10.50 | $11.10 | $11.60 | $12.10 |
| 0.5 | ≤ 0.50 cu ft | $10.50 | $10.90 | $11.35 | $11.80 | $12.50 | $13.00 | $13.60 |
| 0.6 | ≤ 0.60 cu ft | $11.20 | $11.65 | $12.10 | $12.65 | $13.40 | $13.95 | $14.55 |
| 0.7 | ≤ 0.70 cu ft | $12.10 | $12.55 | $13.05 | $13.65 | $14.45 | $15.05 | $15.70 |
| 0.8 | ≤ 0.80 cu ft | $13.00 | $13.50 | $14.05 | $14.70 | $15.55 | $16.20 | $16.90 |
| 0.9 | ≤ 0.90 cu ft | $13.90 | $14.45 | $15.00 | $15.70 | $16.60 | $17.30 | $18.05 |
| 1.0 | ≤ 1.00 cu ft | $14.80 | $15.35 | $15.95 | $16.70 | $17.65 | $18.40 | $19.20 |
Rates are commercial estimates. Verify current rates at Pirate Ship or Shippo before purchasing labels.
Ground Advantage Cubic is consistently $1-2 cheaper per tier than Priority Mail Cubic at the same zone. The tradeoff is 2-5 day delivery versus 1-3 day delivery. For non-urgent e-commerce shipments the savings are real and the delivery window is acceptable for most buyers.
Tier Breakpoint Optimization – Where One Dimension Change Saves Real Money
Because tiers round UP, a package at 0.21 cubic feet pays the 0.3 tier rate. Reducing dimensions so the package calculates to 0.20 cubic feet drops it to the 0.2 tier.
At Zone 5 Ground Advantage Cubic: 0.3 tier = $9.20 vs 0.2 tier = $8.65. Save $0.55 per shipment. At 500 orders per month: $275 per month from one dimension change.
How to find your breakpoints:
Step 1: Calculate your current cubic volume using rounded-down dimensions.
Step 2: Check where your result sits within the tier. If you are at 0.22 cubic feet, you are paying the 0.3 rate but only need to get to 0.20 to drop a tier.
Step 3: Calculate what dimension reduction gets you below the tier boundary.
Step 4: Check whether a packaging change is feasible for your product.
Example: a 9 × 7 × 6 inch box calculates to (8.75 × 7.0 × 6.0) ÷ 1,728 = 0.213 cubic feet after rounding down. Pays the 0.3 tier. Reduce height by 0.25 inches to 5.75 inches: (8.75 × 7.0 × 5.75) ÷ 1,728 = 0.204 cubic feet. Still in 0.3 tier. Reduce to 5.5 inches: (8.75 × 7.0 × 5.5) ÷ 1,728 = 0.195 cubic feet. Now in 0.2 tier. Save $0.55 per shipment at Zone 5 Ground Advantage Cubic.
For comparison against UPS and FedEx on the same dimensions, the DIM Weight Calculator shows all four carriers side by side with USPS Cubic eligibility checked automatically.
Softpack and Padded Envelope Tiers
Poly mailers, padded envelopes, and soft pack packaging use a different tier calculation. Instead of length × width × height, soft packs are measured by the sum of length plus width of the flat unloaded packaging material.
Priority Mail Cubic Softpack tiers:
- Tier 0.1: length + width up to 21 inches
- Tier 0.2: length + width over 21 up to 27 inches
- Tier 0.3: length + width over 27 up to 31 inches
- Tier 0.4: length + width over 31 up to 34 inches
- Tier 0.5: length + width over 34 up to 36 inches
No single dimension can exceed 18 inches. Total cannot exceed 36 inches combined.
The rates for softpack tiers are the same as the box tiers at the same tier level. A Priority Mail Cubic Softpack in tier 0.2 pays the same Zone 5 rate as a box in tier 0.2.
Ground Advantage Cubic has different soft pack tier thresholds from Priority Mail. Check current USPS Postal Explorer for Ground Advantage soft pack tier dimensions before purchasing labels on padded envelopes.
The full comparison of when USPS Cubic beats Ground Advantage standard rates across zones and weights is in USPS Cubic vs Ground Advantage.
See changelog.
FAQ
How many tiers does USPS Cubic pricing have?
Priority Mail Cubic has 5 tiers from 0.1 to 0.5 cubic feet. Ground Advantage Cubic has 10 tiers from 0.1 to 1.0 cubic feet. Both services use the same tier boundaries: each tier covers a 0.1 cubic foot range, and packages round UP to the next tier if they exceed the tier boundary.
How do I calculate which USPS Cubic tier my package falls into?
Measure each dimension and round DOWN to the nearest 0.25 inch. Multiply length × width × height and divide by 1,728. The result in cubic feet determines your tier. If the result exceeds a tier boundary (for example 0.21 cubic feet exceeds 0.20), you round UP to the next tier (0.3). Use the USPS Cubic Calculator to calculate your tier automatically.
What is the cheapest USPS Cubic tier and what size box fits in it?
Tier 0.1 is the cheapest, covering packages up to 0.10 cubic feet. A 6 × 5 × 5 inch box calculates to approximately 0.087 cubic feet and fits in tier 0.1. At Zone 5 Ground Advantage Cubic, tier 0.1 costs approximately $8.10. At Zone 5 Priority Mail Cubic, approximately $8.95. Any package under 0.10 cubic feet with longest side 18 inches or under and weight 20 lbs or under qualifies.
What is the difference between Priority Mail Cubic and Ground Advantage Cubic rates?
Ground Advantage Cubic is approximately $1-2 cheaper per tier at the same zone compared to Priority Mail Cubic. The tradeoff is delivery speed: Priority Mail delivers in 1-3 business days, Ground Advantage delivers in 2-5 business days. Ground Advantage Cubic also allows larger packages — up to 1.0 cubic foot versus 0.5 cubic feet for Priority Mail Cubic.