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US ZIP Code Validator

Everyday

Validate US ZIP codes and ZIP+4 extended codes for correct format instantly. Identifies geographic region from the first digit — client-side, nothing stored.

Reviewed by the thecalcu.com team · Last updated July 20, 2026

What is a ZIP Code?

The US ZIP Code Validator checks whether a US postal code follows the correct USPS format, either a 5-digit ZIP code (XXXXX) or a 9-digit ZIP+4 code (XXXXX-XXXX). It also identifies the geographic zone from the first digit, providing a quick sanity check that the code is in the right part of the country for the intended address.

US ZIP codes range from 00001 to 99950, with the first digit dividing the country into 10 geographic zones (0 for New England/Puerto Rico through 9 for the Pacific states). The ZIP+4 extension narrows the delivery point to a specific side of a street, a building, a floor, or a P.O. Box group, providing the level of precision needed for USPS automation and bulk mailing discount rates.

What the validator checks:

  • 5-digit format: all digits, exactly 5 characters
  • ZIP+4 format: 5 digits, a hyphen, 4 more digits (XXXXX-XXXX)
  • Geographic zone from first digit (0–9)

What it does not check: Whether the specific ZIP code is currently assigned to a geographic area by USPS. Format validation is sufficient for form-field validation and data quality checks; USPS address API verification is needed to confirm active assignment.

For formatting raw ZIP digit strings (without the hyphen) into the correct XXXXX-XXXX format, use the ZIP Code Formatter. For validating both US ZIPs and Indian PIN codes in a combined tool, use the Pincode / ZIP Validator.

All validation is client-side. No data is transmitted.

Why Use a US ZIP Code Validator?

ZIP code format validation is a standard requirement in any US-market address form. Users occasionally enter non-ZIP values (city names, phone numbers, international postal codes) in ZIP fields. A real-time format check prevents non-numeric and wrong-length entries before they reach the database.

E-commerce use case: An Indian e-commerce SaaS accepting US shipping addresses needs to validate ZIP codes in the checkout form before passing addresses to FedEx or UPS shipping APIs. A format validation at the form level prevents API calls with malformed postal codes that would return errors.

Data quality use case: A US customer contact database export contains ZIP codes stored as integers in a spreadsheet, all leading zeros have been stripped (e.g. 06010 became 6010). The validator flags these 4-digit entries, allowing the data engineer to identify and fix the affected rows.

Who Should Use This Validator?

Developers building US-market forms with address fields, checkout flows, shipping integrations, mailing list sign-ups, who need real-time ZIP code format validation.

Data engineers cleaning US address datasets where ZIP codes may have been stored as integers (losing leading zeros), entered in wrong formats, or mixed with Canadian postal codes (which have a letter-digit-letter-digit-letter-digit pattern and would be flagged as invalid).

Indian companies with US operations processing US customer shipping or billing addresses who need to confirm ZIP code format before passing data to USPS, FedEx, UPS, or USPS address verification APIs.

QA engineers building test suites for US address forms who need a reference validator for test assertions.

What Insights Does the US ZIP Code Validator Give You?

A valid result shows the 5-digit base ZIP, the ZIP+4 extension if provided, and the geographic zone corresponding to the first digit. This zone information is a useful sanity check, a California address should have a ZIP starting with 9, not 0 (New England). If the zone doesn't match the city/state, the ZIP is likely a typo.

An invalid result tells you exactly what's wrong: wrong character count, non-digit characters, or an incorrect hyphen position for ZIP+4 format.

How to use this ZIP Code calculator

  1. Enter the ZIP code in the input field, 5 digits (90210) or ZIP+4 format (90210-4567).
  2. Check the Valid/Invalid badge, updates instantly.
  3. Read the details, base ZIP, extension (if any), and geographic zone.
  4. Cross-reference the zone against the expected state, a mismatch suggests a data error.
  5. Format raw digit strings into ZIP+4 using the ZIP Code Formatter if needed.
Show formula & methodology ↓Show less ↑

Formula & Methodology

Format rules:
- 5-digit ZIP: /^\d{5}$/
- ZIP+4: /^\d{5}-\d{4}$/

Geographic zone by first digit:

| First digit | Geographic region |
|---|---|
| 0 | New England, New York, New Jersey, Puerto Rico |
| 1 | New York, Pennsylvania, Delaware, Maryland |
| 2 | Virginia, West Virginia, North/South Carolina, Georgia |
| 3 | Florida, Alabama, Mississippi, Tennessee |
| 4 | Indiana, Kentucky, Michigan, Ohio |
| 5 | Iowa, Minnesota, Montana, North/South Dakota, Wisconsin |
| 6 | Illinois, Kansas, Missouri, Nebraska |
| 7 | Arkansas, Louisiana, Oklahoma, Texas |
| 8 | Arizona, Colorado, Idaho, Nevada, New Mexico, Utah, Wyoming |
| 9 | Alaska, California, Hawaii, Oregon, Washington, Pacific territories |

Valid and invalid examples:

| Input | Valid? | Note |
|---|---|---|
| 90210 | ✓ | Beverly Hills, CA |
| 10001 | ✓ | New York, NY (Empire State Building) |
| 90210-4567 | ✓ | ZIP+4 format |
| 06010 | ✓ | Bristol, CT (leading zero) |
| 9021 | ✗ | Only 4 digits |
| 902100 | ✗ | 6 digits |
| 9021A | ✗ | Non-digit character |
| 90210-456 | ✗ | ZIP+4 extension only 3 digits |

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Frequently Asked Questions

What is a US ZIP code?
A US ZIP code (Zone Improvement Plan code) is a 5-digit postal code used by the United States Postal Service (USPS) to identify geographic delivery areas. Introduced in 1963, ZIP codes range from 00001 to 99950, though not all values in that range are assigned. They help USPS sort and route mail more efficiently. An extended form, ZIP+4, adds a hyphen and four more digits to identify a specific delivery segment within the 5-digit area.
What is the difference between a 5-digit ZIP and a ZIP+4 code?
A 5-digit ZIP code identifies a postal delivery area, typically a city, a neighbourhood, or a portion of a metropolitan area. The ZIP+4 code (also called Plus-4 or ZIP+4 Code) appends four digits after a hyphen (e.g. 90210-4567) that narrow the delivery point to a specific street segment, building, floor, or P.O. Box group. USPS automation equipment uses ZIP+4 for more precise sorting. Both formats are valid, ZIP+4 is optional but preferred by USPS for bulk mailings.
What does the first digit of a US ZIP code mean?
The first digit of a US ZIP code identifies a broad national area: 0 covers New England and Puerto Rico; 1 covers New York, Pennsylvania, and surrounding states; 2 covers Virginia and the Southeast; 3 covers Florida and the South; 4 covers Ohio, Michigan, Indiana, and Kentucky; 5 covers the Upper Midwest; 6 covers Illinois, Missouri, and the Plains; 7 covers Texas and the South Central region; 8 covers the Mountain West and Southwest; 9 covers the Pacific states, Alaska, Hawaii, and US territories.
Does this validator confirm the ZIP code is currently assigned?
The validator checks format only: 5 digits (or 5 digits, hyphen, 4 digits for ZIP+4). It shows the geographic zone based on the first digit but does not query the USPS address database to confirm the specific ZIP is currently in service. Some ZIP codes in the valid numeric range are unassigned, only the USPS address validation API can confirm assignment. For display and form-field format checking, this validator is sufficient.
What is the difference between the US ZIP Code Validator and the Pincode / ZIP Validator?
The [Pincode / ZIP Validator](/pincode-validator/) validates both Indian PIN codes (6 digits, first digit 1–9) and US ZIP codes (5 digits) in a combined tool. The US ZIP Code Validator is dedicated to US ZIP format only, it also supports ZIP+4 (XXXXX-XXXX) which the combined tool does not. Use this tool when you specifically need ZIP+4 validation or geographic zone information.
Is my ZIP code data stored when I validate it?
No, all validation runs entirely in your browser. The ZIP code is never sent to any server, stored, or logged. The tool works offline once loaded.
How is a US ZIP code different from an Indian PIN code?
A US ZIP code is 5 digits (no leading zeros in practice for most assigned codes); an Indian PIN code is always 6 digits where the first digit is never 0. Both are purely numeric. The US has about 42,000 assigned ZIP codes; India has about 19,000 PIN codes. The US uses ZIP+4 (9 digits) for extended precision; India has no extended format. Use the [Pincode / ZIP Validator](/pincode-validator/) to check both formats in one place.
Can a ZIP code start with zero?
Yes, ZIP codes in the 0XXXX range (00001–09999) are assigned to New England and Puerto Rico. Connecticut, Massachusetts, Rhode Island, Vermont, New Hampshire, Maine, New Jersey, New York, and Puerto Rico all have ZIP codes starting with 0. ZIP codes with a leading zero must be stored as strings (not integers) in databases to preserve the leading zero.
How do I use the US ZIP Code Validator?
Enter the ZIP code in the input field, 5 digits (e.g. 90210) or ZIP+4 format (e.g. 90210-4567). The Valid/Invalid badge updates instantly. For valid codes, the details show the 5-digit base, the ZIP+4 extension if provided, and the geographic zone identified by the first digit.
What is ZIP code 00000 or 99999?
Neither 00000 nor 99999 is assigned to a real delivery area by USPS. 00000 is commonly used as a placeholder in databases and test data. 99999 is used in some US military postal addresses. The validator accepts both as structurally valid (correct format) but cannot confirm USPS assignment status. Real ZIP codes in active use range from 00501 (Holtsville, NY) to 99950 (Ketchikan, AK).
What is the format for a USPS address with ZIP+4?
The standard USPS address format places the ZIP+4 code at the end of the last line: CITY, STATE XXXXX-XXXX. For example: 'LOS ANGELES, CA 90210-4567'. The state abbreviation is a 2-letter code (CA, NY, TX, etc.) in uppercase. When formatting ZIP codes in bulk for USPS mailing lists, use the [ZIP Code Formatter](/zip-code-formatter/) to normalise raw digit strings to the XXXXX-XXXX format.
Also known as
check ZIP codeUS postal code validatorZIP+4 validatorUS zip code checkerUSPS postal code check