Project Guide

How to Install a Mailbox

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How to Install a Post-Mount Mailbox
A mailbox on a post.

Learning how to install a mailbox post and the associated box doesn’t mean calling in the professionals. Here’s the step-by-step to help you get the job done.

Dig Post Hole
A person digging a hole for a post.

USPS requirements state that a mailbox can be no taller than 45 inches above street level. Since most streets have a curb, the standard mailbox height is 42 inches above ground level. So, the total height is around 45 inches; 42 inches from the ground, plus the few inches added by the curb.

  • Measure the height of your mailbox post. USPS requirements state that a mailbox height must be 41 to 45 inches above the road's surface. Standard mailbox height above the ground is 42 inches.
  • Mark a spot on your lawn six to eight inches back from your curb. If you do not have a raised curb, contact your local postmaster for guidance.
  • Use a post hole digger to dig a hole for your post at this spot. Dig deep enough that the height of your mailbox above the ground is around 42 inches. Do not dig deeper than 24 inches.
Insert Mailbox Post
A person placing a mailbox post.

Make sure your desired mailbox post meets Federal Highway administration recommendations: stable mailbox posts that can bend or fall to the side if hit by a car. Avoid unyielding supports such as metal or concrete posts, and instead use a 4 x 4-inch wooden support or a 2-inch diameter standard steel or aluminum pipe.

  • Insert the mailbox post into the hole.
  • Prop the post up with support beams on all sides, extending around the outside of the hole. Make sure these are secure and will not shift as the concrete is poured.
  • Measure the height of the mailbox above the ground to ensure it’s around 42 inches.
  • Do not bury your post deeper than 24 inches.
  • Use a level to ensure the mailbox post is straight.
  • If your chosen mailbox post comes with manufacturer's instructions, double-check that you are following those closely while you work through this guide's steps. 
Pour the Concrete
A person pouring concrete into a post hole.

While installing a mailbox without concrete may be possible, long-term installations fare better with the security only concrete can provide. Here’s how to pour concrete to keep post-mount mailboxes in place for the long haul:

  • Prepare a bag of fast-setting concrete mix per manufacturer’s instructions and pour into the hole, around the post.
  • Allow a few inches of space at the top of the hole – do not fill the concrete flush with the ground’s surface.
  • Immediately after pouring, use a level to double-check your mailbox. If it has shifted slightly uneven, adjust now before the concrete begins to dry.

Tip: A 50-pound bag of concrete should suffice for this project.

Allow Concrete to Set
A mailbox post in hardening concrete.
  • Allow the concrete to dry. The length of time this will take depends upon the type of concrete you used – check the concrete label for specifics.
  • Leave the support beams around the mailbox until you are certain the concrete is completely set.
Attach the Mailbox Per Manufacturer’s Instructions
A brown mailbox attached to a mailbox post.

  • Make sure you follow any specific instructions provided by the manufacturer when figuring out how to attach a mailbox to a post.
Add Street Numbers
A red mailbox with white street numbers.
  • USPS requires that each mailbox be clearly labeled with its corresponding house letters and numbers.
  • Add your street address or house number on the side of the mailbox with numbers at least one inch tall.
  • Per USPS guidelines, if your mailbox is on a different street than your home, put your full street address on the mailbox.

Tip: If you are constructing your own mailbox, contact your local postmaster to go over the mailbox plans and confirm the design follows USPS standards.

Dress It Up
A white mailbox in a curb garden.
  • There may be a few inches of empty space in the post hole above the concrete. You can fill this in with soil to bring it level with the surrounding ground.
  • Improve your curb appeal by turning your mailbox area into a small garden in your front yard.
  • Regularly inspect your mailbox to ensure it is holding up well against the weather and normal wear and tear. Once a year, check for loose hinges and rust. If you notice something has obstructed a clear path to the mailbox or that the house numbers have become lost or faded, fix the problem immediately.
How to Install a Wall-Mount Mailbox
A white wall-mounted mailbox.

In some cases, it will be necessary to mount a mailbox directly to a wall rather than installing it as a free-standing structure.

Mark the Wall
A person marking a wall with a level and pen.
  • Hold the mailbox against the wall at its desired installation location. 
  • Double-check that this location is easily accessible from your sidewalk, front steps or porch so that the mail deliverer will not have any trouble finding it.
  • Use a level to ensure you're holding the mailbox flat.
  • Open the mailbox and insert a pencil through the mounting holes on the back of the mailbox to mark the wall.

Tip: Some wall-mount mailboxes come with an installation template that allow you to affix a sheet of paper or cardboard to the wall for easier marking.

Drill Holes
A person drilling a hole in a brick facade.
  • Drill into the wall at each of the points you just marked.
  • You don’t need to drill very deep for this installation. Typically, you can use a 1/4-inch drill bit for brick or masonry walls and a 1/16-inch drill bit for wood walls. 
  • Check the installation instructions that came with your mailbox to double-check the requirements for your individual unit.
Install Mounting Hardware
A person installing wall-mounted hardware.
  • For masonry or brick walls, insert plastic anchors into each drilled hole and tap lightly if necessary.
  • Attach any mailbox hardware necessary to your box or the wall as instructed on your provided installation manual.

Tip: Often, installation hardware is not included with your wall-mounted mailbox. Check the mailbox’s manual for specifics on what you need to purchase additionally for proper installation.

Hang the Mailbox
A person getting mail from a wall mounted mailbox.
  • Insert screws into the top holes and hang on the wall, only twisting the screws in halfway.
  • Rest a level on top of the mailbox to double-check it is flat. Adjust if necessary. 
  • Insert screws into the bottom holes and drill in only halfway, again checking that mailbox is level.
  • Once you’re certain the mailbox is level, drill all screws in securely.

Learning how to install a mailbox is within reach. Whether you prefer post-mounted or wall-mount mailboxes, we can help you find all of the items you’ll need to get the job done quickly and efficiently.

Ready to find the supplies you need in your local store? We can help you locate residential mailboxes, mailbox post kits, post-hole diggers and more. Use The Home Depot app to locate products and check inventory. We'll show you the exact aisle and bay.