How to Write a PO Box Address: Examples

The short answer

Write the box holder’s name on the first line, PO BOX and the box number on the next line, and the city, state, and ZIP Code for that box on the last line: for example JANE DOE, then PO BOX 1234, then ANYTOWN NY 12345-1234. USPS’s standard form is PO BOX with no periods and no # sign, and the box number must sit on the line directly above the city, state, and ZIP Code.

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PO Box address format, line by line

A PO Box address has the same structure as any US mailing address, with the box taking the place of the street. USPS Publication 28 standardizes the box line as PO BOX followed by the number, and the Domestic Mail Manual requires the box number to appear immediately above the city, state, and ZIP Code.

When you give someone your PO Box address, give every line exactly as your Post Office assigned it, including the ZIP+4 if you have it. Capital letters without punctuation match USPS’s preferred style, though neat lowercase is acceptable.

PO Box address example (placeholder details)
Line	What to write	Example
Name	The recipient’s name, or the business name	JANE DOE
Company (optional)	The business name, when you write to a person there	BRIGHT HARBOR DENTAL
Delivery line	PO BOX and the box number, nothing else	PO BOX 1234
Last line	City, two-letter state, and the ZIP Code or ZIP+4 for the box	ANYTOWN NY 12345-1234

PO Box or P.O. Box: which is correct?

Both are understood. The Domestic Mail Manual says Post Office Box and PO Box both designate the service, while USPS’s addressing standard writes the line as PO BOX with no periods. Publication 28 also says punctuation may be omitted from the address block, so PO BOX 1234 is the cleanest choice.

Write PO BOX rather than shortcuts such as BOX 1234, POB 1234, or #1234, which don’t match the USPS standard; a # sign before a number has other meanings in an address. When USPS standardizes an address, it even converts labels such as CALLER, FIRM CALLER, BIN, LOCKBOX, and DRAWER to PO BOX.

Should a PO Box go on address line 1 or line 2?

USPS delivers to the address on the line immediately above the city, state, and ZIP Code. That rule decides where the box goes: when you mail to a PO Box, PO BOX and the number should be the last line before the city line. USPS’s consumer addressing guide puts it more simply: use a PO Box or a street address, but not both.

On online forms with Address line 1 and Address line 2, type PO BOX 1234 in line 1 and leave line 2 blank. Line 2 is meant for apartment and suite numbers.

Some businesses print both a street address and a PO Box on their letterhead. If you copy both, put the one you mean to use directly above the city line and make sure the ZIP Code belongs to that line. If both appear on the same line, USPS delivers to the PO Box.

How USPS reads an address that includes a street and a box
Lines above the city, state, and ZIP Code	Where USPS delivers
100 MAIN ST, then PO BOX 55 on the next line	PO Box 55
PO BOX 55, then 100 MAIN ST on the next line	100 Main St
100 MAIN ST PO BOX 55 on a single line	PO Box 55

Use the ZIP Code that belongs to the box

The ZIP Code must match the address on the line directly above it, which in a PO Box address is the box itself, not the box holder’s home or office. A ZIP+4 can identify a specific group of PO Boxes, so a ZIP+4 copied from a street address won’t be right for a box.

Ask the box holder for the exact city, state, and ZIP+4, or check it with the USPS ZIP Code Lookup. USPS says ZIP Codes for PO Boxes in the same city usually don’t change, and the local Post Office is the place to ask how a box’s ZIP Code is assigned.

PO Box Street Addressing: a street-style address for the box

At some Post Offices, PO Box customers can sign up for Street Addressing. The box then gets a second address: the Post Office’s street address with the box number after a # sign. USPS’s customer agreement gives the example of a box at a Post Office on 500 Main Street, which becomes 500 Main Street #59, followed by the city, state, and the PO Box ZIP Code.

The option exists mainly so private carriers such as UPS, FedEx, DHL, and Amazon can deliver packages to the box; only the Postal Service may deliver to a PO BOX address. Use the exact format the box holder gives you. The agreement requires the # sign and box number and says not to substitute Suite or Apt, while Publication 28 also mentions UNIT where a Post Office allows it.

Street Addressing depends on the location and isn’t available for Caller Service, Reserve Number, or free Group E boxes. USPS’s agreement also says the street-style address can’t be used as the box holder’s residence or place of business in legal documents.

Private mailboxes and campus mailrooms are not PO Boxes

A mailbox rented from a private business is at a commercial mail receiving agency (CMRA), not a Post Office. Those addresses use PMB or # followed by the mailbox number, and USPS prohibits writing PO BOX for them. One format the Domestic Mail Manual shows is the name, then the street address with the PMB on the same line, such as 10 MAIN ST PMB 234, then the city, state, and ZIP Code.

The same goes for box numbers at a college or company mailroom: the Domestic Mail Manual notes that PO Box is used incorrectly in front of a private box number such as a college mailroom’s. Ask the recipient for their exact format.

What you can send to a PO Box

Letters and postcards sent through USPS are delivered to the box. USPS says domestic Priority Mail Express can also go to a PO Box: if the sender requires a signature, USPS leaves a notice in the box so the customer can sign for the item. According to USPS’s PO Box agreement, a package that doesn’t fit is picked up at the service window or from a parcel locker, depending on the location.

Shipments from private carriers need Street Addressing, described above. Certified Mail raises its own questions, so read the Certified Mail guide before you send a time-sensitive notice to a box.

Mailing a letter to a PO Box through IRIS

IRIS’s letter form has no separate PO Box field, and it doesn’t need one. Type PO BOX and the number in the Street address field, leave the Apt, suite, unit field empty, and enter the box’s city, two-letter state, and ZIP Code or ZIP+4. Review the address before checkout: suggestions are advisory and don’t guarantee that the recipient still uses the box.

A one-page black-and-white letter costs $3.20 with First-Class postage included, and Certified Mail can be added for $6.95. IRIS prints and mails individual letters and postcards to US addresses; it doesn’t rent PO Boxes, set up Street Addressing, or receive mail for you.

Sources & further reading

Product details checked against the IRIS API contract when this article was published. Platform references can change; consult the linked documentation when implementing.

Published by IRIS Postal Forms, operated by Great Lakes Computing Office LLC. Send a correction.

Put it into practice

Mail a letter to a PO Box without a trip to the Post Office

Upload a finished PDF, enter the box address in the street address field, and review the full price before checkout. IRIS prints and mails letters to US addresses.

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