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USPS ZIP+4 Lookup Tool (Free)

Enter a full address to get the correct 9-digit ZIP+4 code and USPS-standardized address format. Powered by official USPS data.

Look Up ZIP+4 Code

To look up ZIP+4, USPS requires a full street address plus either city & state or a 5-digit ZIP code.

About ZIP+4 Codes

  • • ZIP+4 is only returned when USPS can match the exact delivery point for your address.
  • • The extra 4 digits narrow down the location—often to a specific street segment, building, or floor.
  • • Using ZIP+4 improves mail sorting accuracy and can help reduce returned or misdelivered mail.
  • • If USPS can't fully verify the address (typo, missing unit, new construction), ZIP+4 may not be available.
  • • This tool uses official USPS address data via The Letter Pilot's integration.

Frequently Asked Questions

What is a ZIP+4 code?
A ZIP+4 code is a 9-digit postal code that adds four digits to the standard 5-digit ZIP code. The extra four digits narrow down the delivery point more precisely—often to a specific street segment, building, or even individual floor.
Why didn't I get a ZIP+4 code?
USPS couldn't fully confirm the exact address. This usually happens when there's a typo, missing unit number, or the address is too new to be in the database. Double-check the spelling, add any missing apartment/suite numbers, and try again.
Do I need ZIP+4 to mail a letter?
No, the 5-digit ZIP code is sufficient for USPS delivery. However, including the ZIP+4 improves sorting accuracy, speeds up delivery, and reduces the chance of your mail being returned or misdelivered.
Is this official USPS data?
Yes. This lookup tool uses the official USPS Address Validation API integrated through The Letter Pilot. Results reflect USPS's current address database.

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