How many digits are in a standard US postal ZIP code?

There are five digits in a standard U.S. ZIP code. The first digit in a ZIP code designates a general postal area from the Northeast (0) to the West Coast (9), with each subsequent digit narrowing the destination to an individual post office.

A standard U.S. ZIP code is read from left to right. The first digit designates a general area of the country, and the next two digits refer to one of the Sectional Center Facilities within that region. The final two digits designate the postal delivery zone or the individual post office that serves addresses with the ZIP code.