ZIP Code vs. ZIP+4: What Is the Difference?

The five-digit ZIP Code

The familiar ZIP Code contains five digits and identifies a general postal delivery area. It is commonly used on letters, packages, forms and online address fields.

The extra four digits

ZIP+4 adds a hyphen and four additional digits to the five-digit code. Those extra digits help identify a more specific delivery segment, such as a block, building, group of apartments or organization. The exact assignment depends on USPS delivery information.

When should you use ZIP+4?

A complete ZIP+4 can improve address matching and mail sorting, but it is not always required when entering an address. Use the ZIP+4 returned by an authoritative address lookup for the exact delivery address; do not guess the final four digits.

A practical example

A ZIP+4 is written in the format 12345-6789. This is a format example only, not a real address recommendation. Always validate the complete address before mailing.