USPS Priority Mail Cubic pricing shipping label on a box

Get USPS Priority Mail Cubic® pricing with no markup or fees

Priority Mail Cubic is a secret service you won't find at the Post Office, but it's the best way to ship small, heavier packages

Yuzen subscription ships with Priority Mail CubicUSPS shipping scaleSansevieria plantYellow measuring tapePriority Mail Cubic Pricing shipping labels
Shipping labels printed by a Dymo 4XL
  • 📦

    Cheapest pricing for small packages

    Priority Mail Cubic is the cheapest, fastest way to ship small packages that weigh between 1 and 20 pounds.

  • Delivery in 1 to 3 business days

    USPS® will deliver Priority Mail Cubic packages to anywhere in the USA (and territories) within 1 to 3 days.

  • 📡

    Free package tracking included

    All Priority Mail Cubic packages included full door-to-door tracking, so you can keep an eye on your shipments.

  • 💥

    $100 insurance included for free

    Priority Mail Cubic postage purchased from Pirate Ship includes $100 of USPS® insurance for free.

  • 💵

    Save up to 89% by using Pirate Ship

    Priority Mail Cubic pricing isn't available at the Post Office and it'll save you up to 89% off retail prices.

  • 🏆

    Cubic is the best shipping service

    Businesses that optimize their packaging for USPS Cubic pricing unlock huge savings and efficiencies.

Calculate your Priority Mail Cubic pricing tier

Victory Coffees ships with Cubic Pricing
Enter your package's outer dimensions
Enter your envelope's empty outer dimensions
Exact Cubic Volume: 0

Get rates BELOW Commercial Pricing for Priority Mail Cubic

Succulent plantBokksu ships with USPS Cubic

Pirate Ship offers Priority Mail Cubic rates BELOW Commercial Pricing® (the deepest discounts publicly available from USPS) with no markup, per-label costs, or monthly fees.

We can't advertise the highlighted rates because they're UP TO $1.02 CHEAPER than Commercial Pricing!
Create a free account & get a rate quote to see these secret rates
Cubic Feet
Up to, not over
0-150 miles
L, 1 & 2
150-300 miles
Zone 3
300-600 miles
Zone 4
600-1000 miles
Zone 5
1000-1400 miles
Zone 6
1400-1800 miles
Zone 7
1800+ miles
Zone 8
Zone 9
Cubic 0.1
Less than
Less than
Less than
Less than
Less than
Cubic 0.2
Less than
Less than
Less than
Less than
Less than
Cubic 0.3
Less than
Less than
Less than
Less than
Cubic 0.4
Less than
Less than
Less than
Cubic 0.5
Less than
Less than
Less than

Priority Mail Cubic is one of the best kept secrets for shipping packages that weigh up to 20 lbs

Shipping labels

Priority Mail Cubic (or "Cubic" as it's commonly called) is a secret sub-service of Priority Mail® that’s usually only offered to businesses who ship at least 50,000 packages per year. But with Pirate Ship you can access even deeper discounts (below Commercial Pricing) with no minimum volume requirements.

The pricing for Priority Mail Cubic is based on the outer dimensions of your package, rather than the weight. There are 5 different tiers of pricing that your package could be in depending upon its size, and any box that's under half of a cubic foot in volume can qualify, as long as none of the dimensions go over the 18" maximum. You can ship up to 20 pounds for no extra cost, making it one of the cheapest shipping services available for small boxes.

To calculate which Cubic pricing tier your package is in:

  1. Measure the outer length, width, and height of your package (18" max in any dimension). If any of the measurements are over the nearest quarter inch, round down to the nearest quarter inch (for example, 5.6" inches turn into 5.5" inches);
  2. Multiply the Length x Width x Height, then divide the result by 1728;
  3. The resulting number is the size of the package in cubic feet, and you can use the Priority Mail Cubic® rate chart above to determine the pricing. Round up fractional results to the next tier (so for example, a package that is 0.24 cubic feet will be in the 0.3 tier).

Note that Priority Mail Cubic packages cannot be larger than 0.5, half of a cubic foot, but larger packages can be sent with weight-based Priority Mail.

Get the cheapest Priority Mail Cubic Softpack pricing

Priority Mail Cubic Softpack labels and shipping envelope

You can also ship soft pack poly or padded envelopes with Priority Mail Cubic Softpack. Cubic Softpack pricing is the same as if you were shipping a box, but the formula for calculating the pricing tier is different.

To calculate which pricing tier a softpack envelope is in:

  1. Measure the Length and Width of the empty envelope or softpack mailer (in inches);
  2. If the measurements exceed the nearest quarter inch, round down to the nearest 1/4" inch (for example, 9.9" inches turns into 9.75" inches);
  3. Add the measurements together and determine which pricing tier your envelope is in:

    Cubic Softpack Tier 0.1 - Length plus Width measures more than 0" up to 21"
    Cubic Softpack Tier 0.2 - Length plus Width measures more than 21" up to 27"
    Cubic Softpack Tier 0.3 - Length plus Width measures more than 27" up to 31"
    Cubic Softpack Tier 0.4 - Length plus Width measures more than 31" up to 34"
    Cubic Softpack Tier 0.5 - Length plus Width measures more than 34" up to 36"

Note that neither dimension can be over 18", and the total size for Priority Mail Cubic Softpack cannot exceed 36". Larger envelopes can be sent via weight-based Priority Mail.

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