ZIP code lookup

How to use it

1. Type a five-digit ZIP code, or a city and state.
2. Read the city, state, county, population and time zone, and the ZIP codes next to it.
3. Click a row to look at that ZIP code.

5 practical uses

1. Find the city and the state for a ZIP code on a form or a label.
2. Check a ZIP code's county and time zone.
3. List all the ZIP codes of a city for a mailing.
4. Look at where a ZIP code is on the map.
5. Check the population of a ZIP code for a market estimate.

The maths behind it

The ZIP code data holds one point per code: the population-weighted centre of the ZIP Code Tabulation Area. Neighbours are the codes with the smallest haversine distance from that point, and the direction is the initial bearing to each.

Notes

ZIP code positions and populations are the 2020-census ZIP Code Tabulation Areas from SimpleMaps' free database (CC BY 4.0), 33,000 of them. Each is one point, the centre of the area, so a ZIP code counts as inside or outside the circle by that point; a big rural ZIP code is only partly inside in truth. Post-office-box and military ZIP codes are included where they have a position.

The county is the one that holds most of the ZIP code. The population and the county population are approximate; the time zone is the IANA zone of the ZIP code's centre. To find the ZIP code where you are, see what ZIP code am I in.