Area Code Finder by ZIP Code, With Time Zone and Local Time

How to read the result

• Codes for the ZIP code's place. When phone exchanges have a rate center in the ZIP code's main place, those codes come first, with each code's share of those exchanges. A rate center is the geographic point a carrier uses to rate calls; NANPA lists one for every NPA-NXX block.
• Codes for the county. Counties are bigger than most ZIP codes, so a large county can show four or five codes. Smaller places usually narrow it to one or two.
• Overlays. Where NANPA lists an overlay complex, the codes cover the same ground and every call needs 10 digits. Our area-code directory lists each code's overlay codes on its own page.
• Time and daylight time. The time uses your browser's clock and time-zone database, so it follows daylight time (March 8 to November 1 in 2026), the places that never change their clocks, and the Navajo Nation, which does.

How the finder works

A ZIP code is a mail-delivery route, not a place, and NANPA, which assigns area codes and phone exchanges, publishes no ZIP-code or locality data. Its own website says so: it does not have the locality a phone exchange serves and points to rate centers as the clue. So the finder joins three public data sets.

1. ZIP code to place and county. The Census Bureau's 2020 ZIP Code Tabulation Area (ZCTA) relationship files give each ZCTA its main place and county, with the share of land in each. A ZCTA is the Census Bureau's approximation of a ZIP code area. PO-box-only and single-building ZIP codes have none, so the finder says so.
2. Phone exchange to county. NANPA's central-office-code assignments list every NPA-NXX with its rate center. We match each rate center to a place and county in the Census Gazetteer and USGS place names. That is how the same exchanges feed the county lists on each area-code page (98.5% of exchanges matched on our last run).
3. ZIP code to time zone. The U.S. Department of Transportation and Bureau of Transportation Statistics publish the nine U.S. time-zone polygons, compiled from the boundary descriptions in 49 CFR Part 71. We take the zone at the Census centroid of the ZIP code area. We then apply the places that skip daylight time ( DOT): Hawaii, American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, the Virgin Islands and most of Arizona.

Limits: the match is only as good as rate centers, which follow telephone wire centers and not county lines; a ZIP code on a county line may also use the neighbor's codes; and one ZIP code, West Wendover, Nevada (89883), is set to Mountain time by hand because 49 CFR 71.9(b) puts that city on Mountain time. For a split area code, such as 850, enter a ZIP code to see which zone applies. There are no pages for individual ZIP codes: the finder looks each one up in your browser.

Data sources and licensing

The build scripts (scripts/geo/build_zip_lookup.py and build_area_zones.py) write the two lookup tables the page uses. The ZIP table is a static file of about 1 MB (about 380 KB compressed) that your browser downloads the first time you enter a ZIP code; the file is the same for everyone and reveals nothing about what you typed.

Why an area code is only a starting point

The FCC's porting guide says you can keep your number when you change providers and stay in the same geographic area, and may not be able to if you move to a new one. Mobile numbers, though, are in practice carried everywhere; the CFPB's debt-collection rule says mobile numbers “are not associated with a place.” Callers can also fake a local number (the FCC calls it neighbor spoofing). Read more in our guides to area code time zones and which area codes are scams. If you need to know whether it is a lawful hour to call someone, use the calling-hours checker.

Related

• Can they call me now?
• Area code time zones
• All US area codes
• Complaints by state
• Neighbor spoofing

FAQs