GlossaryRates and surcharges
Cubic pricing
A USPS pricing method that charges small, dense packages by volume tier and zone rather than by weight.
Cubic pricing is a USPS rate structure for small, heavy packages. Instead of pricing by weight, it groups packages into volume tiers based on their outer dimensions and charges by tier and zone, up to a maximum package weight and size.
It is offered on certain services, such as Priority Mail and USPS Ground Advantage, and is generally available through commercial pricing, for example via shipping software, rather than at a retail counter.
For dense products in small boxes, cubic pricing can be cheaper than weight-based rates. Measuring accurately matters, because the tier is set by the largest dimensions rounded down to the nearest quarter inch.
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