About PlainZIP

PlainZIP answers the questions people bring to a ZIP code: where it is, which town and county it belongs to, which ZIP codes a city or county has, and what the area is like in figures. It covers 41,706 ZIP codes, from the residential delivery areas the Census Bureau maps to the PO Box, single-organization and military codes that have no area.

What you get

Each ZIP code page gives the ZIP's town, county share and state, a map with the ZIP codes around it, where it ranks inside its own town and county, and its people, income, homes and businesses, each with the survey or file it comes from. City, county, state and three-digit prefix pages list every ZIP code they contain, on a map and in a table you can sort. Rankings and research compare ZIP codes across the country with their methods stated.

A ZIP code page also names the Census places its land lies in (a ZIP code's postal name is often not the city it sits in: much of 90210 lies in the city of Los Angeles), its House districts, its metro area and the neighborhoods GeoNames places inside it, so the page answers "what city is this ZIP code" as precisely as the public record allows. Where a county or a three-digit prefix holds the same ZIP codes as a city, PlainZIP lists them once, on the city's page, and says so.

What PlainZIP is not

PlainZIP is a reference, not a service of the Postal Service: it does not assign ZIP codes, look up street addresses or ZIP+4 codes (the USPS ZIP Code Lookup does), or rate places as good or bad to live in. Its figures are the public record's, with the record's limits: survey estimates carry margins, and a ZIP code is a mail route that the Census Bureau approximates with an area. It gives no city or county totals; those belong to profiles of places as places.

Who publishes it

PlainZIP is owned by Kiznis Studio, an independent publisher of public-data reference sites based in Lithuania. It is not affiliated with the United States Postal Service or with any agency whose data it shows. How the data is built, checked and kept current is set out on the methodology page; the rules for what PlainZIP publishes are in the editorial policy.

PlainZIP has published U.S. ZIP code pages since February 22, 2026; the current site, rebuilt around the lookup and the public files above, dates from October 9, 2026.

Contact

Questions, corrections and data requests go to hello@plainzip.com. A reported error is checked against its source and, when confirmed, fixed and listed on the corrections page.