The U.S. postal ZIP code for boxes is not one single code; it depends on the specific mailing address or P.O. Box. USPS says you can look it up by address or P.O. Box to get the correct ZIP or ZIP+4 code.

What to use

  • ZIP code : the 5-digit code used for U.S. mail routing.
  • ZIP+4 : the ZIP code plus 4 extra digits for more precise delivery.
  • For a box, the right code is the one assigned to that street address or P.O. Box , not to the box itself.

If you meant a PO Box

A P.O. Box has its own ZIP code or ZIP+4 in many cases, and USPS recommends looking it up by the box number and city/state.

Example

If you are mailing to a package drop box or storage box, you still use the recipient’s actual ZIP code, not a special “box code”.

If you want the exact ZIP code, send the street address or P.O. Box details and I can help you identify the format to use.