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ZIP code validator

Check a US ZIP code's format, see its first-digit region, and look up the town, state and map point for the five-digit code.

Input

ZIP code check

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Enter a US ZIP code to check its 5-digit (or ZIP+4) format.

A US ZIP code is five digits, optionally followed by a hyphen and four more (ZIP+4). When the Census dataset is available, the five-digit code is also checked against current ZIP Code Tabulation Areas. Some USPS codes, including codes used only for PO boxes, may not have a matching Census ZCTA.
Format
5 · ZIP+4
Check
Structure

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This ZIP code validator does two things. First it checks the format in your browser: five digits, optionally followed by four more as ZIP+4. It accepts 12345-6789, 123456789 or 12345 6789. When the format is right, it looks the five-digit code up in the Census Bureau's ZIP Code Tabulation Areas and in the Zippopotam.us place database. Then it tells you the town and state, a map point and the land area, plus the broad region the first digit stands for.

How to validate a ZIP code

  1. Enter a ZIP like 90210 or a ZIP+4 like 20500-0003.
  2. The format check runs as you type. Anything other than 5 or 9 digits is rejected with a reason.
  3. A valid code gets its first-digit region, for example 9 is West: AK, CA, HI, OR, WA.
  4. A moment later the lookups fill in the place name, state, coordinates and land area, when they're found.

How US ZIP codes are structured

USPS brought in five-digit ZIP codes in 1963. The first digit is a group of states, numbered roughly from 0 in the Northeast to 9 on the West Coast. The first three digits together point to a sectional center facility, and the last two narrow it to a post office or delivery area. ZIP+4, added in 1983, tacks on four digits for a block, a building or a set of PO boxes.

What this ZIP code check can't confirm

  • Whether USPS currently delivers to the code. The Census ZCTA list isn't the USPS list.
  • Whether the +4 suffix is real. Only the first five digits are looked up.
  • PO-box-only and single-business ZIPs often have no ZCTA, so they can show as not found even when they're real.
  • Whether a ZIP belongs with a particular street address. That takes USPS address verification.

Frequently asked questions

What does ZIP code validation check?

The format, in your browser, and then whether the five-digit code appears in the Census ZCTA data and the Zippopotam.us place list. Matching a ZCTA is good evidence the code is real, but it isn't a USPS confirmation.

What do the digits in a ZIP code mean?

The first digit is a regional group, running from 0 in the Northeast to 9 in the West. The first three together identify the sectional center facility, and the last two pick out the local post office or delivery area. The optional four-digit add-on narrows things to a delivery segment.

How is ZIP+4 different from a standard ZIP?

It adds a hyphen and four digits to the five-digit ZIP. The extra digits pick out a block face, a building or a group of PO boxes so mail can be machine-sorted more precisely.

Does this tool send the ZIP codes I enter anywhere?

The format check is local. For a valid code, the five-digit part, never the +4, goes to our server, which looks it up in our Census ZCTA dataset and asks Zippopotam.us for the place name.

Built and maintained by Bipul Kumar. Found a wrong number or a broken result? Tell me and I'll fix it.