How do USPS Zones work?
For certain labels, the USPS determines pricing by shipping distance, which they do with Postal Zones. Zones are based on the distance a parcel or a piece of mail travels from point A to point B, and are calculated from the first three digits of your origin and destination zip codes. Zone 1 would represent the closest (and therefore cheapest) areas to mail from your zip code, while Zone 8 would represent the farthest (and most expensive) areas.
You can consult USPS rate charts to figure out your shipment's postal zone, but you can also quickly look it up using our Zone Lookup Tool.