Frequently asked questions
What is a ZIP code?
ZIP stands for Zone Improvement Plan. The five-digit code was introduced by the United States Postal Service in 1963 to make mail sorting faster and more efficient. The first digit represents a broad geographic area, and the remaining digits narrow it down to a specific post office or delivery area.
Why does a city have more than one ZIP code?
Large cities are divided into multiple delivery zones, each with its own ZIP code. New York City, for example, has hundreds. This tool shows the most well-known ZIP(s) for each city.
What is a ZIP+4 code?
The extended ZIP+4 format adds a hyphen and four more digits to narrow down to a specific block or building. This tool uses the standard 5-digit ZIP codes only.
Is my data uploaded anywhere?
No. The ZIP code database is built into this page and everything runs offline in your browser. Nothing is sent to a server.