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County by ZIP code

Every county a ZIP touches, with the share of each. Paste a list for a CSV.

Up to 1,000 ZIPs at once. Everything runs in your browser.

One ZIP or a thousand

  1. 1

    Type or paste

    One ZIP for a quick answer, or a whole column from a spreadsheet. Commas, spaces and new lines all work.
  2. 2

    See every county

    Each county the ZIP touches, with its share of the land and its FIPS code. The map draws the county lines over the ZIP.
  3. 3

    Download the CSV

    One row per ZIP: main county, FIPS, share and every other county. Ready for Excel or Google Sheets.

County lines are messier than you think

30%

of ZIP areas touch 2+ counties

10,186 of 33,791

~6,300

have 10%+ in a second county

a real share of homes

2,546

touch three or more

137

cross a state line

Where the county data comes from

Each ZIP is matched to counties with the Census Bureau’s 2020 ZIP Code Tabulation Area to county relationship file, which measures how much of every ZIP area lies in every county. Results list every county with at least a sliver of the ZIP, largest share first. Lookups run in your browser from a static copy of that data, so a pasted list never leaves your device.

The CSV has one row per ZIP:

  • county and county_fips: the county with the largest share of the ZIP
  • county_share_pct: that county’s share of the ZIP’s land
  • other_counties: every other county, with FIPS and share

FIPS codes keep counties with the same name apart: there are 30 Washington Counties. Format the column as text in Excel so leading zeros stay. For anything official about one address, like property tax or voter registration, pin the exact spot or check with the county itself.

Questions people actually ask

What county is my ZIP code in?

Type the ZIP above. If the whole ZIP is in one county, you’ll see it straight away. If it’s split, you’ll see every county it touches and how much of the ZIP’s land is in each. For a split ZIP, pin the exact spot on the ZIP code finder to see the county for one home.

Why is my ZIP code in more than one county?

ZIP codes follow mail delivery routes from a post office, and those routes cross county lines freely. In 2020 Census data, 30% of ZIP code areas touch more than one county and 2,546 touch three or more.

How do I convert a list of ZIP codes to counties?

Paste the list into the box, separated by commas, spaces or new lines, and press Find the county. You get a table and a CSV with the main county, its FIPS code, its share of the ZIP and any other counties. Up to 1,000 ZIPs at a time.

What do the percentages mean?

Each figure is the share of the ZIP’s land area that lies in that county. It’s a good guide to where most addresses are, but not a population count: a small slice of land can hold a dense neighborhood.

Why does my ZIP show no county?

PO Box ZIPs, single-building ZIPs and some military and organization ZIPs have no area on Census maps, so they can’t be matched to a county boundary. The result still shows the city they’re delivered from.

Keep exploring

My ZIP codeYour ZIP, lit up on the map, with the numbers behind it.Open What county am I inYour county, lit up with its border and how far the county line is.Open What time zone am I inYour zone, UTC offset and daylight saving, plus every US zone at a glance.Open ZIP code mapEvery US ZIP code with its boundary. Hover, tap, color by data.Open Radius mapDrag a circle and watch every ZIP inside light up. Copy or export.Open ZIP GuessrFive ZIPs a day. Tap where each one is, keep your streak, share your score.Open ZIP codes near meEvery ZIP around you, nearest first, with distance and direction.Open ZIP distanceMiles between two ZIP codes, drawn as a flight path.Open

Updated 2026-11-10 · Where the data comes from