How to Address a PO Box Correctly
Quick Answer: PO Box Address Format
- Line 1: Recipient Name
- Line 2: PO Box [number]
- Line 3: City, State ZIP Code
- Critical: Use the PO Box ZIP Code, not your home ZIP or the surrounding area ZIP
Addressing mail to a PO Box requires a specific format to ensure USPS delivers it to the correct location. Unlike street addresses, PO Box mail goes directly to a post office for pickup. Using the wrong format can delay delivery or cause your mail to be returned. This guide covers the exact USPS format, common mistakes, and special situations.
In This Guide
When to Use a PO Box
Understanding the benefits of using a PO Box can help you decide if it's the right choice for your mail needs:
- Privacy: Keep your home address off public records and marketing lists
- Security: Protect mail from theft when you cannot receive deliveries at home
- Frequent travelers: Never miss mail when you are away from home
- Home delivery issues: Avoid problems with unmarked addresses or inaccessible rural locations
- Small business mail: Maintain a professional mailing address separate from your residence
Standard PO Box Address Format
The correct format for addressing mail to a PO Box is:
- Line 1: Recipient name
- Line 2: PO Box [number]
- Line 3: City, State ZIP Code
Example:
John Smith
PO Box 1234
Austin, TX 78701
Important Formatting Rules
USPS has specific requirements for PO Box addresses:
- Write "PO Box" not "P.O. Box" or "Post Office Box" (though USPS will accept variations)
- Do not include a street address on the same label unless using Street Addressing (see below)
- Use the ZIP Code assigned to the post office, not the recipient's home ZIP
- The PO Box number must match the ZIP Code's post office location
PO Box Street Addressing
Some post offices support Street Addressing, which allows packages from carriers like UPS and FedEx to be delivered to your PO Box. This format uses the post office's street address with the PO Box number as a unit number:
Example:
John Smith
123 Main St #1234
Austin, TX 78701
The "#1234" corresponds to PO Box 1234. Not all post offices offer this service. Check with your local post office or look for "PO Box Street Addressing" on USPS.com.
Finding the Correct ZIP Code
PO Boxes have their own ZIP Codes, which may differ from the surrounding area. To find the correct ZIP:
- Ask the PO Box holder for their assigned ZIP Code
- Use the USPS ZIP Code lookup tool at usps.com
- Call the destination post office directly
Using the wrong ZIP Code can send your mail to the wrong post office entirely.
Common Mistakes to Avoid
❌ Common PO Box Addressing Mistakes
- Including both a street address and PO Box (mail may go to the street address instead)
- Using your home ZIP Code instead of the PO Box ZIP Code
- Forgetting to include "PO Box" before the number
- Writing the box number without the PO Box designation
- Using abbreviations USPS cannot process (use "PO Box" not "POB" or "Box")
Sending Packages to a PO Box
USPS delivers packages to PO Boxes, but size restrictions apply. The package must fit in the box or be small enough for the post office to hold. Large packages may require pickup at the counter. UPS and FedEx do not deliver to PO Boxes unless the post office participates in Street Addressing.
Send Mail to PO Boxes Online
Skip the post office and send letters to PO Boxes through The Letter Pilot. We print, address, and mail your letters using USPS First Class or Certified Mail.
Send a Letter Online →Frequently Asked Questions
Can I send certified mail to a PO Box?
Yes. USPS delivers certified mail to PO Boxes. The recipient signs for it at the post office counter or receives a notice to pick it up.
What happens if I include both a street address and PO Box?
USPS delivers to the address on the line directly above the city/state/ZIP. If the street address is above the city line, it goes there. Put the PO Box on the line above the city to ensure PO Box delivery.
Can UPS or FedEx deliver to a PO Box?
Not directly. However, if the post office offers Street Addressing, you can use that format to receive UPS and FedEx packages at your PO Box.
Do I need to include the recipient's name?
Yes. USPS requires the name to match an authorized user of the PO Box. Mail addressed to unauthorized names may be returned.
What if I do not know the PO Box ZIP Code?
Ask the recipient or use the USPS ZIP Code lookup tool. Never guess, as mail sent to the wrong ZIP goes to the wrong post office.
Can I send international mail to a PO Box?
Yes, if the destination country uses PO Boxes. Format requirements vary by country.
Is PO Box capitalized?
USPS commonly uses "PO Box" in all caps (P.O. BOX), but variations like "PO Box" or "P.O. Box" are also accepted.
Mail Letters to PO Boxes with Confidence
Letters submitted before 8 PM ET are printed and mailed the next business day. Add tracking with Certified Mail for important correspondence.
Send Certified Mail →Related Guides
- How to Address an Envelope
- PO Box Costs and Sizes
- How to Avoid Mail Returned to Sender
- Return to Sender Guide
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