USPS Shipping Calculator

This calculator rebuilds the way USPS prices a domestic parcel. It starts with the two ZIP codes. Each one maps to an approximate location, and the great-circle distance between them falls into one of eight zone bands: under 50 miles is Zone 1, 51 to 150 miles is Zone 2, and so on up to Zone 8 for anything past 1,800 miles. Alaska, Hawaii, Puerto Rico, and the Pacific territories always price at the top zone.

Next it works out what USPS will actually bill you for. If you enter the box measurements and the box holds more than one cubic foot, the tool divides length by width by height by 166 to get the dimensional weight, then bills whichever is higher, that figure or the scale weight. Anything over a pound rounds up to the next whole pound, which matches how the Postal Service charges. It also checks the 70-pound, 108-inch length, and 130-inch length-plus-girth limits, and stops with a clear message if the parcel breaks any of them.

The price for each service comes from published 2026 retail rate bands. The calculator interpolates between anchor weights and applies the zone multiplier for that service, then rounds to the nearest nickel. Flat Rate options run alongside, priced the same regardless of weight or zone, with a check on whether your box actually fits inside each one.

Treat the output as a planning estimate. Buying a label online costs less than the retail counter prices modelled here.