USPS Mailbox Standards

Mailbox standards in the US are specified and approved by the US Postal Service (USPS). US mailboxes can be...

  • Curbside -- this is the most common
  • House-mounted, or
  • A slot in the door

The last 2 types must be authorized by your local postmaster. 

USPS Approval

All manufactured curbside mailboxes must be approved by the US Postmaster General. If it is approved it will have "U.S. MAIL" (in minimum of 0.5" high letters) and "Approved By The Postmaster General" (in minimum of 0.18" high letters) on the mail delivery door, or below the mail slot for locked boxes.

In fact, as a general rule any change to your mailbox or mailbox position should first be cleared with your local postmaster

Custom Built Mailboxes

Given the restrictions it's amazing there are any interesting mailboxes in the US at all! 

However, it is possible to make (or have someone make) a custom mailbox for you. It should meet the same mailbox standards of size, strength and quality as those for approved manufacturers (see the standards information below). It will also need to be approved. Your local postmaster has the authority to approve one-off boxes.

You may also decorate your mailbox and the post it's on, provided the decoration doesn't interfere with delivery or collection of mail.

Curbside Mailbox Specifications

Mailbox Types

Since February 8, 2001 (STD-7B), the USPS mailbox standards allow for 3 designs...
  • Traditional -- the familiar domed rectangular shape. This type cannot have a lock
  • Contemporary -- any design that isn't traditional, but that meets the capacity specification, but isn't larger than the maximum specification dimensions. This type cannot have a lock
  • Locked -- mailboxes designed to secure delivered mail

Each of the designs may be for limited service (that is there's no flag and therefore no collection service) or for full service (both delivery and collection of mail).

The standard contains detailed specification diagrams (see below for where to get the standard).


  • A house number at least 1" high on the right hand side of the box (that is, facing the direction the post person will usually approach the mailbox from). If your box is in a cluster the number should be on the front of the box
  • If the mailbox is not on the street of the mailing addressing, include the street name as well
  • You may also add your name, but you don't have to


Don't forget to contact your local post office before you install a new box!

Generally your box should be installed as follows...

  • On the right hand side of the road where the postal worker can safely deliver mail without getting out of the delivery vehicle
  • The inside floor of the mailbox, or the mailbox slot for locked designs, should be 41-45" above the road
  • The delivery face of the mailbox should be set back 6-8" from the curb or road edge
  • The front of the mailbox should be kept clear for easy access by the postal worker

Other Considerations

To ensure your mail service continues uninterrupted also take the following into account...

  • The mounting post and arm is not regulated by the USPS. However, no part of them should stick out past the front of the closed mailbox
  • Only items delivered by the US Postal Service may be placed in your US approved mailbox. However, you may attach a separate holder for non-mail items such as newspapers. This container must not intefere with mail delivery, should not stick out past the front of your closed mailbox and can not have advertising on it
  • A locking device may not be retrofited
  • The mailbox and its post may not display any advertising
  • You may decorate your mailbox and post as long as any art or accessories do not interfere with the mail service or create a hazard
  • It's up to you to maintain your mailbox and its installation

Where to Find the USPS Mailbox Standards

You'll find a brief summary here: USPS standards for residential mailboxes. You'll find more detailed US mailbox specifications here

If you are a manufacturer of mailboxes for the US market you will need your mailbox approved by the USPS -- to get a copy of the latest, full, official USPS mailbox standard (STD-7B) write to USPS Engineering, the address is on this page.