Traditionally, the USPS set rates based only on the weight of a package. Packages 16oz or less used First Class Mail Package and over 16oz used Parcel Select Ground. With the introduction of faster delivery Priority Mail and Priority Mail Express, the USPS began using zone-based pricing, which means rates are based on weight AND distance. Since January 2019, zone-based pricing has applied to all USPS package classes*.
*Zone-based pricing does not apply to USPS Flat Rate boxes and envelopes.
The USPS has 9 shipping zones - 8 in the continental United States and 1 for outlying territories. These zones are dynamic based on the distance from the shipper's zip code.
Stamps.com automatically calculates the correct rate based on the weight of your package, your ship from zip code, and the zip code of your recipient. You should familiarize yourself with zone-based pricing to understand how it affects your business, especially if you offer free shipping. We've included several examples below to help illustrate how zone-based pricing works.
In this first example map, the shipper is located in the Los Angeles area. Note how the different zones spread out across the country. Zone 1 is closest to the shipper, while zone 8, encompassing most of the Eastern United States, is furthest away.
In this second example, the shipper is located in the Chicago area. Note how their zones are related to their location, spreading out the further south, west, and east you go.
In this third example, the shipper is located in the geographic center of the United States: Lebanon, Kansas. Note that only a few areas are more than six zones away.