A curbside mailbox should sit 41 to 45 inches above the road surface, measured to the bottom of the box or the point where mail goes in. The front of the box should be 6 to 8 inches back from the face of the curb or the edge of the road. That is the USPS guidance, and your local postmaster can adjust it for your street.
Those two numbers decide whether your carrier can reach the box from the vehicle window. Get them right and almost any approved box on a solid post will pass. If you are buying a complete mailbox with post, this guide shows how to measure so the finished height lands in range, plus the placement rules people overlook.
USPS mailbox height requirement
USPS mailbox guidelines say: "Position your mailbox 41 to 45 inches from the road surface to the bottom of the mailbox or point of mail entry." The curbside mailbox standard, USPS-STD-7C, is a little more precise. It measures to the inside floor the carrier sets mail on, or, for locking boxes with a mail slot, to the lowest edge of the slot.
| Mailbox type | Measure from the road surface to | Target |
|---|---|---|
| Standard non-locking box (traditional or contemporary) | The floor of the box where mail sits | 41 to 45 in. |
| Locking box with an incoming mail slot | The bottom edge of the slot | 41 to 45 in. |
| Large-capacity or package box | The inside floor where the carrier places mail | 41 to 45 in. |
The point of the range is simple: the carrier has to reach the box from the vehicle window. Too low and they stretch down; too high and they reach up over the door frame.
How far from the curb should a mailbox be?
USPS says 6 to 8 inches from the front face of the curb, or the road edge, back to the mailbox door. In other words, the door of the box is set back from the curb line, not hanging over the road.
- Too close and passing traffic, mirrors and plows clip it.
- Too far and the carrier cannot reach it without getting out, which is the one thing the rules are written to avoid.
- No raised curb? USPS asks you to contact your local postmaster. STD-7C measures from the road edge where there is no curb, but your postmaster decides.
How to measure your mailbox height correctly
The most common mistake is measuring from the lawn instead of the road. Yards are often higher or lower than the street, and USPS measures from the road surface.
- Lay a straight board or tight string level from the road surface (or curb top, then subtract curb height) out over the spot where the post will go.
- Measure up from that line 41 to 45 inches. Mark the height where the floor of the box, or the bottom of the slot, must land.
- Measure how far the ground at the post is above or below the road. Subtract it (if the ground is higher) or add it (if lower).
- Check the box: how far is its floor or slot above the point where it bolts to the post or arm? Subtract that too.
- What is left is the height the top of the post or the mounting arm needs to sit above the ground.
- Mark the setback: 6 to 8 inches back from the curb face to where the door will be. Remember the box usually sits forward of the post on an arm.
A worked example
Your lawn sits 4 inches above the road. You want the floor of the box at 43 inches above the road, the middle of the range. So the box floor needs to be 39 inches above your lawn. If your box's floor is about 1 inch above its mounting surface, the top of the post or arm needs to be about 38 inches above the lawn. Measure your own box; designs differ.
Mailbox post height and burial depth
Post length is the above-ground height you just worked out plus the buried depth. USPS (quoting Federal Highway Administration guidance) recommends a 4x4 wooden post or a 2-inch diameter steel or aluminum pipe, buried no more than 24 inches, so it gives way if a car hits it. Heavy pipe and concrete posts are on USPS's list of supports to avoid.
Manufactured posts are sized so the box lands in range when installed per the instructions. A few examples from the posts we sell:
- The Mail Boss In-Ground Post is 43 inches long and, per the product listing, is typically buried about a foot and set in concrete. Mail Boss also makes 27-inch and 37-inch posts that bolt to a base plate on concrete.
- The Mail Boss Surface Mount Post is made for mounting to a 4 to 8 inch high sidewalk or curb, which is why it is shorter.
- Decorative sleeves like the Mayne Signature Plus Mail Post slide over a standard 4x4 wood post, so you set the 4x4 at the right height and the sleeve follows. Mayne recommends a box at least 7 inches wide for its arm.
For choosing post length and material, see our mailbox post buying guide. Call 811 before you dig; utility lines often run along the road.
USPS mailbox placement rules
Height is only half of it. The Domestic Mail Manual (DMM 508.3.2.6) says a curbside mailbox must be placed so the carrier can deliver safely and conveniently without leaving the vehicle. The other rules (approval, numbers, flags, posts) are in our USPS mailbox requirements guide.
Which side of the road?
On new rural routes, every box goes on the right-hand side of the road in the carrier's direction of travel. Elsewhere, it is required where traffic makes delivering to the left side unsafe or illegal. A box across the road from your house is normal. If it stands on a different street from your house, put your street name and house number on it.
Keep the approach clear
DMM 508.3.1.4 makes it the customer's job to keep the approach clear. Parked cars, trash cans, overgrown shrubs and snow banks in front of the box can get delivery held. Postmasters can withdraw delivery if carriers cannot reach the box.
Near your driveway
USPS does not set a distance from your driveway. Many towns and state highway departments do have rules for objects in the road right-of-way, so check with them, your HOA, and your postmaster before you dig.
Rural roads, ditches and slopes
Rural boxes follow the same 41 to 45 inch rule, measured from the road surface. Where the shoulder drops into a ditch, the post can end up much longer than usual; measure from the road, not from the ditch bottom. If a ditch or slope makes the 6 to 8 inch setback impossible, ask your postmaster. A post with an extended arm can put the box at the road edge while the post stands back on firm ground. More on this in our rural mailbox guide.
Snowplow country
USPS suggests a semi-arch or extended-arm support where snow removal is a problem, so the plow can clear near or under the box without hitting the post. Keep the box at legal height; do not lift it out of range to dodge the plow. Our guide to protecting your mailbox from snowplows covers swing-away posts and what to do after a hit.
How high should a wall-mounted mailbox be?
The 41 to 45 inch rule is for curbside boxes served from a vehicle. USPS does not set a height for a wall-mounted mailbox at your house. Its guidance is to put the box near the main entrance where the carrier can easily see it, and to get your postmaster's permission before switching from curbside to a wall box. In practice, mount it where the carrier can open the lid without bending or reaching over steps or railings. Browse wall mount mailboxes if you have door delivery.
Mail slots in a door are different: the bottom of the slot must be at least 30 inches above the finished floor, with a clear opening of at least 1-1/2 by 7 inches.
Cluster and apartment mailbox heights
Centralized boxes have their own rules. For wall-mounted 4C apartment mailboxes, the USPS-STD-4C mounting drawings put no customer compartment floor lower than 28 inches and no tenant lock higher than 67 inches above the finished floor, with at least one compartment under 48 inches.
Shop mailboxes and posts
Browse complete mailbox and post packages or a mailbox post on its own. Have an awkward curb, ditch or slope? Contact us with a photo and we will help you pick a setup that lands at the right height.
Frequently asked questions
How high should a mailbox be from the ground?
USPS measures from the road surface, not the ground. The bottom of the box or the mail slot should be 41 to 45 inches above the road. If your lawn is higher than the road, the box will sit less than 41 inches above the lawn.
How far from the road should a mailbox be?
6 to 8 inches from the front face of the curb, or the road edge, back to the mailbox door. Without a raised curb, ask your local postmaster where they want it.
How deep should a mailbox post be buried?
USPS recommends no more than 24 inches for a 4x4 wood post or 2-inch pipe so it can give way if hit. Manufactured posts list their own depth; follow the instructions and call 811 before digging.
What happens if my mailbox is too low or too high?
Your carrier or postmaster may leave a notice asking you to fix it. Until you do, delivery can be delayed or held if the carrier cannot safely reach the box from the vehicle.
Does a wall-mounted mailbox have a height requirement?
USPS sets no height for wall boxes at the house. Put it near the main entrance where the carrier can see and reach it, and get your postmaster's permission before switching from curbside.
Which side of the road should my mailbox be on?
The right-hand side in the carrier's direction of travel on new rural routes, and wherever left-side delivery would be unsafe. Your postmaster can tell you what applies on your street.
******It is always recommended to contact your local postmaster prior to installation. While most of our mailboxes are USPS-approved your local postmaster may have specific preferences in terms of mailbox types and installation location******
