You can ship packages to a PO Box, and the mechanics depend on the carrier. USPS delivers to every PO Box using any of its standard services. UPS, FedEx, and DHL can’t drop a package into a PO Box directly, but they can get one there through hybrid services that hand the last leg to USPS, or through a USPS feature called Street Addressing that assigns your box a physical street address. Shipping packages to a PO Box works reliably once you match the carrier to the right method.
USPS Reaches Every PO Box
PO Boxes are USPS infrastructure, so USPS has direct access to all of them. Every standard shipping service works: Ground Advantage, First-Class Mail, Priority Mail, and Priority Mail Express. If the sender has a choice, USPS is the simplest path and avoids the complications that come with the workarounds below.
UPS, FedEx, and DHL: The Hybrid Workaround
Private carriers cannot place packages into PO Boxes. A standard UPS or FedEx shipment addressed to a PO Box will usually be returned to the sender.
The workaround is hybrid shipping: the private carrier hauls the package across the country and hands it to USPS for final delivery. UPS SurePost supports PO Box destinations across all 50 states, APO/FPO addresses, and U.S. territories.1UPS. About UPS SurePost FedEx Ground Economy (formerly SmartPost) does the same thing on the FedEx side. Both are contract-based services aimed at lighter, non-urgent shipments, so not every seller offers them at checkout.
Street Addressing: A Physical Address for Your Box
Some Post Office locations offer Street Addressing, which gives your PO Box a real street address. Instead of “PO Box 456,” you use the Post Office building’s actual street address with your box number attached as a unit number. Private carriers deliver to the building, and USPS staff sort the item into your box or a parcel locker.2USPS. PO Boxes
Not every Post Office participates. USPS’s addressing standards note the option is available “in some locations,” so check with your local branch or during online signup.3Postal Explorer. Publication 28 – Postal Addressing Standards – Section: 284 PO Box Street Addressing When it’s active, you can receive packages from UPS, FedEx, DHL, and Amazon at your PO Box without relying on hybrid services, provided shipments comply with USPS mailing standards.2USPS. PO Boxes
Amazon Orders
Amazon ships to PO Boxes only when it assigns USPS as the carrier. If the order is routed through Amazon’s own delivery network or a private carrier, the PO Box address won’t work and checkout may block it. Certain categories are excluded regardless of carrier: Amazon Pharmacy prescriptions, Amazon Fresh grocery orders, and oversized or overweight items exceeding USPS size limits. Same-Day and Amazon Day deliveries require a street address because they use Amazon’s own drivers.
How to Address the Package
Standard USPS Format
For regular USPS shipments, put the recipient’s name on the first line, “PO Box” and the box number on the second line, then the city, state, and ZIP code. USPS recommends writing “PO Box” without periods after the letters.2USPS. PO Boxes
Street Addressing Format
When you’re using Street Addressing for a private carrier, put the Post Office’s physical street address on the first line, then your box number preceded by “#” or “UNIT” on the second line, followed by city, state, and ZIP.3Postal Explorer. Publication 28 – Postal Addressing Standards – Section: 284 PO Box Street Addressing The street line tells the private carrier where to deliver; the box number tells USPS staff where to sort it on arrival.
What Happens When the Package Arrives
PO Boxes come in five sizes, and the largest measures only 22.5 by 12 by 14.75 inches.4USPS. PO Box Sizes Most parcels beyond a padded envelope won’t physically fit inside a box. When that happens, USPS either places the package in a parcel locker and leaves the locker key inside your PO Box, or leaves a notification slip directing you to the retail counter.2USPS. PO Boxes
If your item lands in a USPS Smart Package Locker, you have five calendar days to retrieve it before the access code expires and the package moves to the counter.5USPS. USPS Smart Package Locker Counter-held packages are generally kept up to 15 days. Priority Mail Express is the exception, at 5 days.2USPS. PO Boxes Miss the window and the package goes back to the sender.
What Can’t Be Shipped Directly to the Box
Anything requiring a signature won’t go into the box. USPS leaves a notice, and you sign for the item at the counter. This covers accountable mail: registered mail, certified mail, and insured packages above a certain value.6USPS. USPS Mail Requiring a Signature – Accountable Mail
Hazardous materials face strict rules across all USPS shipping. Flammable liquids, explosives, and pressurized containers are either prohibited or subject to tight packaging and labeling requirements. Cash on Delivery (COD) service is not available for PO Box addresses.2USPS. PO Boxes
The Liability Gap on Hybrid Shipments
Hybrid shipping has one trap worth knowing about. When a package moves through UPS SurePost or FedEx Ground Economy, there’s a handoff point where the private carrier gives the package to USPS. After that handoff, the private carrier’s liability ends. UPS’s SurePost terms state that UPS has “no liability for any loss of, or damage to, any goods while in the care, custody or control of the USPS” and cap overall liability at $100 per package.7UPS. UPS SurePost Terms and Conditions
FedEx Ground Economy works the same way. Claims are capped at $100 per package plus any shipping charges already paid, FedEx won’t reimburse for damage that happened after USPS took possession, and claims must be filed within 90 days of the package entering the FedEx network.8FedEx. FedEx Ground Economy Outbound Service Claims Guidelines For anything worth more than $100, add insurance or ship through USPS directly with a service that includes tracking and coverage.