USPS Cubic Rates

Please note that these rates were only available to very large shippers with a volume of over 250.000 Priority Mail packages per year. However, we are now able to offer this service at a much lower requirement (to check and see if this option is available for you, please find Express 1’s contact information here)
Since the pricing for these rates is based on the volume of the package instead of the weight, cubic rates are ideal for small, heavy packages. Any package that measures ‘0.50 cubic feet or less’ and is ‘20 pounds or less‘ is eligible. Please find the cubic measurement calculation below:
Cubic Feet = Length X Width X Height / 1728
Also note that the length, width, and height measurements should be rounded down to the nearest 0.25 inch. Here’s an example for a package that measures 6-1/8″ × 5-7/8″ × 6-3/8″:

6 × 5.75 × 6.25 / 1728 = .125 cubic feet

There are 5 tiers for cubic pricing:

Tier 1 – mailpieces measuring up to .10 cubic foot
Tier 2 – mailpieces measuring more than .10 up to .20 cubic foot
Tier 3 – mailpieces measuring more than .20 up to .30 cubic foot
Tier 4 – mailpieces measuring more than .30 up to .40 cubic foot
Tier 5 – mailpieces measuring more than .40 up to .50 cubic foot

So our example above would fall into Tier 2. Let’s say this package weighs 4 pounds and is a zone 7 shipment. This would typically cost $13.12 via Priority Mail. However, the cubic price for this package is significantly lower.

Whenever you receive cubic rates through a different USPS provider connected to your Appath account (such as, go ahead and choose a Priority service for that provider, a package type and then simply enter the weight dimensions for the shipment. The provider will then automatically switch to your agreed upon cubic rates, if they are cheaper than the Priority ones.
Please also make sure that the package doesn’t have any dimensions (on all sides) larger than 18″ (check this article for more info).