Validate Zip Code Field For Free - Validate Zip Code

For example, 40202 is in Louisville, 50309 in Des Moines, 60601 in Chicago, 63101 in St. Louis, 77036 in Houston, 80202 in Denver, 94111 in San Francisco, 98101 in Seattle, and 99950 in Ketchikan, Alaska (the highest ZIP Code).

A valid postal code depends on where you live. The specific order of the numbers of a ZIP code are important and can be used to help identify what state an individual lives in and where their mail is sorted. The first three digits of a ZIP code correspond to the central mail processing facility used to sort the mail.

11111 is not a valid 5 digit ZIP Code, but there are valid ZIP Codes that start with 111: 11101, 11102, etc. Once position 28 was changed to Y, then MSP considered 11111 as an Invalid zip, because it looked at all 5 digits.

To validate a zip code: Use the RegExp. test() method to check for a regular expression. The regular expression should check if the value consists of 5 digits or 5 digits followed by a hyphen and 4 digits. If the condition is met, the zip code is valid.

Look Up a ZIP Code? By Address. Enter a corporate or residential street address, city, and state to see a specific ZIP Code?. Find by Address. By City and State. Enter city and state to see all the ZIP Codes? for that city. Find by City & State. Cities by ZIP Code? Enter a ZIP Code? to see the cities it covers.

Postal codes that don't exist in the system often represent obscure or otherwise small geographical zones with minimal internet activity. Additionally, certain ZIP or postal codes that are in close proximity to or overlap with other ZIP or postal codes may be considered invalid.

If the zip check has failed, it's because the bank/credit company is telling us that the zip code does not match the one it has on file. If the cardholder has recently moved, it may take their bank a while to have the correct zip code on file for them.