You can find Small, Medium, Large, and Specialty sizes (like the APO/FPO box for military mail). đź›’ Third-Party Alternatives
Offers packs of boxes (though usually, these are still fulfilled through the USPS partnership). where can you buy usps flat rate boxes
If you need boxes in bulk, you can order them for free on the USPS Postal Store. You can find Small, Medium, Large, and Specialty
Find the for your specific package weight. You can find Small
They are shipped to your home or business for free. Quantities: Usually available in packs of 10 or 25.
Sometimes sells lots of boxes or pre-packed "shipping kits," though it's often more expensive than getting them directly from the source.