To ship to a PO box, send the package with USPS and write “PO BOX” and the box number on the delivery line, followed by the city, state and the ZIP Code of the Post Office where the box is. UPS and FedEx don’t deliver to PO boxes. The exception is when the box holder has signed up for USPS Street Addressing and gives you the Post Office’s street address with their box number.
Table of Contents
- Which Carriers Can Ship to a PO Box?
- How Do You Address a Package to a PO Box?
- Can UPS or FedEx Deliver Using USPS Street Addressing?
- What Happens if the Package Is Too Big for the Box?
- How Do You Ship to a PO Box Step by Step?
- What About Special Items and International PO Boxes?
- Frequently Asked Questions
Which Carriers Can Ship to a PO Box?
USPS is the only carrier that delivers directly to PO boxes, because the boxes sit inside Post Offices. Every domestic USPS service can be addressed to a PO box: USPS Ground Advantage, Priority Mail, Priority Mail Express, Media Mail and First-Class Mail.
UPS’s Terms and Conditions of Service say plainly that UPS does not deliver to a P.O. Box and doesn’t accept APO or FPO military addresses. A UPS package addressed to a PO box can be delayed, isn’t covered by any UPS Service Guarantee, and is subject to an address correction charge. FedEx’s express and ground networks also need a street address.
Economy services that hand parcels to USPS for the last mile, such as UPS Ground Saver, have reached PO boxes at times. Coverage under those arrangements has changed since 2025, though, and they’re usually contract services. Don’t count on one unless your account terms confirm that it delivers to PO boxes. To be sure a parcel reaches a PO box, buy a USPS label.
How Do You Address a Package to a PO Box?
USPS addressing standards put the box number on the delivery address line, the line just above the city, state and ZIP Code. Use this format:
| Line | What to write | Example |
|---|---|---|
| 1 | Recipient’s full name | JANE DOE |
| 2 (optional) | Company or organization | DOE CRAFTS LLC |
| 3 | PO BOX and the box number | PO BOX 1234 |
| 4 | City, state and the ZIP Code of the box’s Post Office | SPRINGFIELD IL 62701-1234 |
Use the ZIP Code assigned to the box, not the recipient’s home ZIP Code, which is often different. Ask the recipient for the full ZIP+4 if they have it. Leave out the periods and write “PO BOX” rather than “Post Office Box No.”. Our guide to sending mail to a PO box covers letters and envelopes in the same format.
Don’t put a street address and a PO box on the label together unless you mean to. When both appear, USPS delivers to whichever address is on the line directly above the city, state and ZIP Code. If you need both on the label, put the PO box on that line.
Can UPS or FedEx Deliver Using USPS Street Addressing?
Yes, at participating Post Offices. USPS Street Addressing gives PO box holders a street-style address, the Post Office’s own street address followed by “#” and the box number. Packages from other carriers, including UPS, FedEx, DHL and Amazon, can then be delivered to the box. USPS says the service is subject to availability and restrictions, and the box holder has to enroll in it.
Only use this format if the recipient confirms they’ve enrolled, and copy the address exactly as they give it, for example “123 MAIN ST #1234”. Writing “Apt” or “Suite” in front of the box number can cause the package to be returned. If you’re not sure, ship with USPS to the standard PO BOX address instead.
What Happens if the Package Is Too Big for the Box?
Packages that don’t fit in the box still get delivered. USPS leaves a slip in the box so the holder can pick the package up at the counter during business hours, or puts it in a secure parcel locker, including USPS Smart Lockers at select locations. Packages that need a signature work the same way: a notice goes in the box, and the holder signs at the counter. Box holders who set up the free Signature on File service can have those items left in the box or a parcel locker.
Most Post Offices offer five box sizes. The table shows what each size typically holds, according to USPS.
| Box size | What fits (per USPS) |
|---|---|
| XS (Size 1) | 10–15 letters and 3 rolled magazines |
| S (Size 2) | 15+ letters, 5 rolled magazines, or 1 Small Priority Mail Flat Rate Box |
| M (Size 3) | Large envelopes and stacked magazines, plus 2 Small Flat Rate Boxes |
| L (Size 4) | Small and Medium Flat Rate Boxes, with room for 10–15 letters |
| XL (Size 5) | Multiple packages |
If you choose your own box, our guide to UPS box sizes lists standard dimensions you can match against these. Large items such as a computer screen never fit a PO box, so the recipient will collect them at the counter. Our guide on how to ship a monitor covers the packing. Recipients who are choosing a box can compare the sizes in our USPS PO box cost guide.
How Do You Ship to a PO Box Step by Step?
- Get the full PO box address from the recipient, including the box’s ZIP Code, and ask whether they use Street Addressing.
- Pack the item in a sturdy box with cushioning, and weigh and measure it.
- Choose a USPS service. Ground Advantage takes 2–5 days, Priority Mail 2–3 days, and Priority Mail Express 1–3 days with a money-back guarantee.
- Buy the label with the address in PO BOX format. You can compare USPS rates for your package in the ParcelPath calculator.
- Drop it off or schedule a free USPS pickup, and share the tracking number with the recipient.
ParcelPath is free and gives up to 89% off USPS, with no subscription or per-label fees. If you don’t have a printer, USPS Label Broker lets the Post Office print the label from a code on your phone. Our step-by-step guide to shipping a package covers packing and drop-off in more detail. Online sellers should also collect a street address at checkout for UPS orders, as our small-business shipping guide recommends. That way a PO box order can switch to USPS automatically. If you also need pickup, freight or same-day options, our list of the best shipping services and solutions compares them.
What About Special Items and International PO Boxes?
USPS mailing rules are the same whether the address is a box or a street. Books and other educational materials can go by USPS Media Mail to a PO box, and our guide on how to ship books explains how to pack them. Restricted items such as liquids must follow USPS packaging rules, as our guide on how to ship liquids explains.
Perishables are riskier to send to a box, because a counter pickup can add a day or more before the food reaches a refrigerator. Use Priority Mail Express and follow our guide to shipping perishable food. Remote areas rely on PO boxes heavily. For mail to Alaska, see our state-by-state guide to shipping within the USA, and for Hawaii see our guide to shipping to Hawaii. In both places USPS is often the most practical carrier.
Many countries have post office boxes too. USPS hands international mail to the destination’s postal service, which can usually deliver to its own box addresses. Private couriers generally need a street address and a phone number. Destination guides such as shipping to the Philippines and shipping to China, along with our international shipping hub, cover each country’s address and customs rules. To find the right counter for drop-off, use our guide to USPS locations. If you need a price first, our shipping calculator guide explains how to get one.
Frequently Asked Questions
Can UPS ship to a PO box?
No. UPS’s Terms and Conditions of Service state that UPS does not deliver to a P.O. Box, and packages addressed to one may be delayed, lose any service guarantee and incur an address correction charge. The workaround is USPS Street Addressing, where the box holder gives you the Post Office’s street address plus “#” and the box number.
How do you write a PO box address on a package?
Write the recipient’s name on the first line, then “PO BOX” and the number on the delivery line, then the city, state and ZIP Code of the Post Office where the box is located. Use the box’s ZIP Code, not the recipient’s home ZIP Code. Avoid putting a street address on the same label.
What happens if a package doesn’t fit in the PO box?
USPS leaves a pickup slip in the box, and the package is held at the counter during business hours or placed in a secure parcel locker. Packages that need a signature also generate a notice. Box holders with the free Signature on File service can have those items left in the box or a locker instead.
Can you track a package sent to a PO box?
Yes. USPS Ground Advantage, Priority Mail and Priority Mail Express all include USPS Tracking to PO box addresses. Tracking may show the package as delivered, or as available for pickup, once it reaches the box’s Post Office, even if the recipient hasn’t collected it from the counter or locker yet.
Sources
- USPS: PO Boxes (Street Addressing, box sizes, slips and parcel lockers, Signature on File)
- USPS Publication 28: Post Office Box addresses
- USPS: Mail and Shipping Services (delivery times)
- UPS Tariff/Terms and Conditions of Service – United States (Section 14, P.O. Boxes)
Part of our USPS Locations guide. Related: USPS Shipping: Rates, Tracking & Services, USPS Collection Boxes.
