USPS Cubic Rate Calculator
USPS Ground Advantage Cubic and Priority Mail Cubic are US domestic services. International postage is not quoted.
USPS Cubic pricing charges by package volume rather than weight. Priority Mail Cubic uses five tiers up to 0.5 cubic feet. Ground Advantage Cubic uses ten tiers up to 1.0 cubic feet. To qualify, weight must be 20 pounds or under and the longest side must not exceed 22 inches. This calculator checks eligibility, assigns a cubic tier, and shows the cubic rate versus standard Ground Advantage at your zone. All calculators support both imperial (inches and pounds) and metric (centimeters and kilograms) units via the toggle at the top of each form.
USPS Cubic pricing can be significantly cheaper for small, heavy items (up to 20lb). Check if your package qualifies and identify its cubic tier. Not sure if your packaging is efficient? The DIM Weight Calculator's smart tip box shows exactly how much billable weight you can save by adjusting your box dimensions and flags USPS Cubic eligibility automatically.
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Cubic is $2.52 cheaper per shipment at Zone 5. At Zone 8 the same package is $4.52 cheaper with Cubic.
Compare Cubic and standard rates by zone
Commercial Ground Advantage vs Ground Advantage Cubic (Notice 123, July 12 2026). Difference is Cubic cheaper, standard cheaper, or a tie—not assumed Cubic savings.
| Zone | USPS Ground Advantage | Ground Advantage Cubic | Difference per Shipment | Monthly (100 pkgs) |
|---|---|---|---|---|
Zone 1 | $9.70 | $8.39 | Cubic $1.31 | $131.00 |
Zone 2 | $9.76 | $8.45 | Cubic $1.31 | $131.00 |
Zone 3 | $10.14 | $8.81 | Cubic $1.33 | $133.00 |
Zone 4 | $11.02 | $9.23 | Cubic $1.79 | $179.00 |
Zone 5Selected | $13.48 | $10.96 | Cubic $2.52 | $252.00 |
Zone 6 | $15.89 | $12.83 | Cubic $3.06 | $306.00 |
Zone 7 | $17.12 | $13.48 | Cubic $3.64 | $364.00 |
Zone 8 | $19.19 | $14.67 | Cubic $4.52 | $452.00 |
Zone 9 | $19.19 | $14.67 | Cubic $4.52 | $452.00 |
Frequently Asked Questions
Essential answers on USPS Cubic qualifications, tier calculations, dimension limits, and software support.
What is USPS Cubic pricing and how does it work?
USPS Cubic pricing charges by volume rather than weight for packages with a longest side of 22 inches or under and weight of 20 pounds or under. Priority Mail Cubic uses five tiers from 0.1 to 0.5 cubic feet. Ground Advantage Cubic uses ten tiers from 0.1 to 1.0 cubic feet. Zone determines the rate within each tier. For small dense packages shipped to higher zones cubic is typically cheaper than standard Ground Advantage weight-based pricing.
How do I know if my package qualifies for USPS Cubic pricing?
A package qualifies if the longest dimension is 22 inches or under, actual weight is 20 pounds or under, and volume is within the service limit: 0.5 cubic feet for Priority Mail Cubic or 1.0 cubic feet for Ground Advantage Cubic. Volume is length times width times height in inches divided by 1,728. A 10 x 8 x 6 inch package is 0.28 cubic feet and lands in tier 0.3.
What are the USPS Cubic tiers in 2026?
Priority Mail Cubic has five tiers from 0.1 to 0.5 cubic feet. Ground Advantage Cubic has ten tiers from 0.1 to 1.0 cubic feet. Each tier covers a 0.1 cubic foot range and packages round up to the next tier if they exceed a boundary. Rates within each tier vary by destination zone from Zone 1 through Zone 9.
Is USPS Cubic available through all shipping platforms?
No. USPS Cubic rates are not available through all shipping platforms. Pirate Ship automatically checks Cubic eligibility on every shipment and shows the cheaper option between Cubic and standard Ground Advantage. Shippo and ShipStation also support USPS Cubic pricing. eBay Labels does not currently offer USPS Cubic pricing meaning eBay sellers shipping cubic-eligible packages through eBay Labels pay standard Ground Advantage rates and miss the Cubic savings. Shopify Shipping does not natively surface USPS Cubic rates. See the Shopify Shipping guide for the workaround. For sellers who ship cubic-eligible packages regularly using a platform that supports automatic Cubic routing can save hundreds to thousands of dollars per month.
Tools That Work Alongside This Calculator
Recommended software for shipping label discounts and rate comparison.
EasyShip
Shipping SoftwareCompare real shipping rates across 550 plus carriers including surcharges before you buy the label. See the real all-in cost in seconds with no monthly fee.
ShipStation
Shipping SoftwareAutomate USPS Cubic and Ground Advantage shipping at discounted rates. ShipStation compares rates across 40 plus carriers and prints labels in bulk with no per-label fees.
Shippo
Shipping SoftwareBuy discounted USPS Cubic and Ground Advantage labels in seconds. Shippo connects to all major carriers and shows real-time rates so you can ship at the lowest available price. Free to start.