Priority Mail Cubic is a type of USPS Priority Mail that's priced based on the dimensions of your package instead of the weight. With this you can save up to 90% off the cost of the label.
You can ship packages that are up to half of a cubic foot in volume with this service (which is 12x12x6 inches, or other combinations that make the same volume) and your packages can weigh up to 20 lbs. Note that to qualify for Cubic rates, the maximum size for any dimension is 18 inches.
Depending on the size of your package, there are 5 pricing tiers it will fall into. It’s a good idea to plan your packaging to fit within the smallest tier possible for your package’s content, because it can drastically lower your costs.
To calculate which of the 5 tiers your package will be in you can use the manual formula below:
For example, to calculate the Cubic tier for a box that is 12.3" x 9.5" x 3":
Note that you can also use a padded envelope or poly softpack, but it changes the formula used to determine your pricing tier.
Cubic-priced mailpieces may not be rolls or tubes.
Once you know which USPS Cubic pricing tier your package is in, you can use the rate chart below to determine what it will cost to ship your package, or use our USPS rates calculator.
Other shipping software adds tons of markup on top of the actual Priority Mail Cubic rates. Pirate Ship is the only shipping software that passes through the deepest discounts available for Priority Mail Cubic for free, with no markup, fees, or minimum volume required.