USPS Mailbox Regulations (Size, Height, Dimensions + More)

Whether mounted next to the front door, or standing firmly on the curb, mailboxes are one of those things that are easy to overlook, but essential to have.

As a result, most people probably don’t give much thought to their mailbox, but there’s actually quite a lot that goes into where they’re located, what they look like, and how they operate. We’ll share those details and more in this article, so read on!

What Are USPS’ Mailbox Regulations In [currentyear]?

Curbside mailboxes must be between 18 9/16” to 22 13/16” long, and 6” to 15” tall. They must also be 11” wide. Their height must be between 41” to 45” above the ground, and be located 6” to 8” back from the curb. Door slots must be located at least 30” off the ground.

If you still have questions about your mailbox, then be sure to read this comprehensive guide for more useful information!

What Are USPS’ Requirements for Mailboxes?

If you’ve lived in your house for a while, or are moving into a house that already has a mailbox set up, you probably haven’t given much thought to USPS’ mailbox requirements.

Believe it or not, there are quite a few, so let’s take a closer look at what they are in this section.

Types of Mailboxes Allowed

USPS allows for 3 different types of mailboxes when it comes to individual houses, condos, or duplexes. These are curbside, wall-mounted, and door slot mailboxes.

Apartment complexes or housing developments may have cluster or community mailboxes. Such designs will have been pre-approved by USPS ahead of time. Therefore, they are not the focus of this guide.

In most cases, your mailbox needs to carry the postmaster general’s seal of approval (wall-mounted and door slots don’t have this requirement).

This seal certifies that the mailbox meets size and durability requirements.

Custom-made mailboxes are considered acceptable if they meet established standards.

You can review the standards by writing to the following address:

MERRIFIELD VA 22082-8101

8403 LEE HWY



Size of Mailbox

According to the postmaster general’s guidelines, curbside mailboxes must be between 18 9/16” to 22 13/16” long, and 6” to 15” tall. They must also be 11” wide.

Wall-mounted mailboxes don’t have any size requirements, but they should be large enough to accommodate a normal day’s mail volume.

Additionally, door slots must have an opening of at least 1 ½ ″ x 7.″

Mailbox Placement

  • Curbside Mailboxes

Your mailbox should be positioned 41” to 45” from the road surface to the bottom of the mailbox or point of mail entry.

In addition, your mailbox should be located 6” to 8” from the curb. If you don’t have a curb, contact your local postmaster for guidance.

Curbside mailboxes should be placed on the right-hand side of the road, and face outward so mail carriers can access it easily without having to leave their vehicle.

Your mailbox can be placed on either side of your driveway, provided that it isn’t blocked or obstructed by anything.

If you’re unsure on which side to place your mailbox, either ask your letter carrier what they prefer or follow what your neighbors have done.

In terms of your mailbox’s post, it should be buried 20” to 24” deep.

  • Wall-Mounted Mailboxes

This type of mailbox should be placed near the main entrance of your house so the mail carrier can easily see it.

  • Door Slots

Door slot openings must be at least 30” above the floor. In addition, horizontal slots must have a flap hinged at the top, while vertical slots must be hinged on the opposite side from the door’s hinges.

If you elect to install an inside hood for privacy reasons, the hooded portion must not be below the bottom line of the slot in the outside plate (if the hood is horizontal).

If the hood is vertical, it must not be beyond the sideline of the slot in the outside plate nearest the hinge edge of the door.

At its greatest projection, the hood must not be less than 2 1/16” beyond the inside face of the door.

Additional Considerations

If you opt for a mailbox with a lock, make sure the slot is large enough to accommodate your daily mail volume.

In addition, the protective flaps on locking mailboxes must be oriented inward so that mail carriers can place mail inside without additional effort.

Can the Post Office Tell You Where to Put Your Mailbox?

Can the Post Office Tell You Where to Put Your Mailbox? USPS

As mentioned above, USPS does have some regulations about where mailboxes should be located (especially for curbside mailboxes).

Still, it’s important to note that USPS does not legislate the location (or relocation) of residential mailboxes on a national level.

Rather, local postmasters make regulations for mailbox placement based on what’s best for their geographic location and mail service.

Therefore, if you’re installing a new mailbox or moving an existing mailbox, it’s important to check with your local post office first.

Can I Just Put up a USPS Mailbox?

Before installing a new mailbox, moving an existing mailbox or replacing your mailbox, you should contact your local postmaster for approval.

Local postmasters have specific regulations when it comes to mailbox placement that you need to comply with, in order to ensure consistent mail delivery.

These regulations are in place to make sure your mailbox is located in an area that doesn’t block other driveways or roads.

They’re also there to make sure mailboxes are located in places deemed safe for a mail carrier to make deliveries.

Can I Move My USPS Mailbox?

If your mailbox is hard to access, or is located somewhere that makes it easy to vandalize, you’re probably thinking about moving it to a better location.

Usually, you can move your USPS mailbox without too much hassle, provided you follow the tips below.

1. Contact your local postmaster first

Each postal jurisdiction has specific rules about where mailboxes can be located, so you’ll need to make sure your plans comply. 

It’s also important to inform the post office once you’ve actually moved your mailbox.

Mail carriers have delivery paths they have to follow during their route. If your mailbox isn’t located in its usual spot, you may miss your delivery.

2. Consider the weather and mailbox exposure

When deciding where to move your mailbox, it’s important to consider weather conditions.

For example, you may think that moving your mailbox in front of your driveway is convenient, but this location could get buried by snow plows in the winter.

Additionally, try to choose a spot where your mailbox will be shaded from the sun.

Mailboxes that sit in the sun can heat up quickly, and can result in damage to makeup, medications, or other heat-sensitive items you have delivered.

  • Consider sight-lines to the mailbox

It’s a good idea to put your mailbox in a location that’s visible from inside your house.

Not only will this allow you to check for mail without having to go outside in inclement weather, but it may also help to deter thieves and vandals.

How Much Clearance Is Needed Around a Mailbox?

USPS requires a 30-foot approach around a mailbox- 15 feet before and 15 feet after the mailbox.

This means not only keeping trash cans, vehicles, and other objects away from your mailbox, but also making sure paths are cleared of snow and ice.

Can I Paint My Mailbox?

Most mailboxes come in traditional colors like black, white or brown, but USPS allows curbside mailboxes to be any color.

Therefore, you’re free to be creative with your mailbox’s color or design. In fact, there are currently no restrictions regarding the color of mailboxes in the United States.

That being said, there are some restrictions. One is that your mailbox and post are prohibited from having any advertisements on them.

In addition, your mailbox must include several key elements.

First, your house or apartment number should be written on the front or flag side of the box.

Next, the letters should be at least 1” tall, and be in a color that contrasts with the box color.

In addition to the street name and house number, you can include your name, but are not required to do so.

Finally, if your mailbox is located on a different street from your house or apartment, put your full street address on the box.

Do You Need to Have a Red Flag on Your USPS Mailbox?

While most mailboxes have a red flag on them, they are not required by USPS.

For example, if you have no need to send outgoing mail, then you won’t get much use out of a mailbox flag.

If you do decide to have a flag on your mailbox, be aware that it doesn’t have to be red.

USPS allows mailbox flags to be any color besides blue, brown, white, yellow, or green. Such colors blend into the surroundings, and make it difficult for mail carriers to see the flag.

In addition to these restrictions, a mail flag must be in a color that contrasts with the mailbox itself. Again, this is so the flag is easy to see.

Therefore, if your mailbox is red, you might opt for a black or gray flag instead.

What Are USPS’ Requirements for a Mailbox Post?

USPS doesn’t have specific rules about mailbox posts, but some recommendations are provided.

For one, mailbox supports should be stable, but bend or fall if a car hits them.

That means you should avoid unyielding or potentially dangerous supports, like heavy metal pipes, concrete posts, or farm equipment (e.g. a milk jug filled with concrete).

Items like a 4″ x 4″ wooden support or a 2″-diameter steel or aluminum pipe make good mailbox supports.

If you choose to use wood, make sure it’s treated to prevent rot and insect infestation.

USPS notes that about ⅓ of the post should be in the ground. That means a typical mailbox sits about 20” to 24” in the ground.

You don’t want to go deeper than 24,” as this could lead to hitting pipes, wires, or other lines running underground.

What’s more, a deep post will be more difficult to remove later on if you decide to replace or reposition it.

Most people choose to secure their mailbox post with concrete, but this isn’t required. You can use dirt to fill in the hole.

Lastly, when it comes to attaching additional receptacles to the post (i.e. for newspaper delivery), USPS has a few guidelines that must be followed.

A newspaper receptacle is acceptable so long as it meets the following requirements:

  • It Doesn’t touch the mailbox or use any part of the mailbox for support
  • Doesn’t interfere with the delivery of mail, obstruct the view of the mailbox flag, or present a hazard to the mail carrier or vehicle
  • Doesn’t extend beyond the front of the mailbox when the box door is closed
  • Doesn’t display advertising, except the publication title

To know more, you can also read our posts on how does USPS mailbox installation works, why is USPS mail forwarding not working, and USPS mail handler.


There’s a lot to keep in mind when installing or moving a mailbox, but as long as you stay in touch with your local post office about any changes you’re making, the process should be smooth.

What’s more, the post office can give you advice about where to put your mailbox, what kind to buy, and how to install it.

Photo of author

Marques Thomas

Marques Thomas graduated with a MBA in 2011. Since then, Marques has worked in the retail and consumer service industry as a manager, advisor, and marketer. Marques is also the head writer and founder of

Leave a Comment