Pick a curbside box or a door slot and tell us about the ground. You get the height and setback the Postal Service asks for, the post, and the size of your house numbers.
Mailbox height
41–45″ from the roadto the box’s bottom · aim for 43″ · 6–8″ back from the curb
Quick answer: the USPS mailbox height is 41–45″ from the road surface to the bottom of the box (or wherever the mail goes in), and the box’s front sits 6–8″ back from the curb. Measure from the road, not the grass: if the ground at the post is higher, the box sits lower above it. Use a 4×4 wood post or a 2″ pipe, buried no more than 24″. House numbers need to be at least 4″ tall.
How to use the mailbox height calculator
- Pick a curbside box, or a door slot or wall box.
- Say whether the road has a raised curb. The setback is measured from it.
- Enter how far the ground at the post sits above the road (type a minus if it is below). The height rule is measured from the road, so this moves where you mark the post.
- Enter how far the house numbers are from the street: you get the size that reads from there. Copy link keeps the result.
The rules behind the numbers
Height and setback: the Postal Service’s own rule
USPS asks you to put the mailbox 41″ to 45″ from the road surface to the bottom of the box or the point where the mail goes in, and 6″ to 8″ back from the curb, so the carrier can reach it from the vehicle without the box hanging over the road. Without a raised curb, USPS asks you to check with your local postmaster.
From the road, not the ground
The 41–45″ starts at the road. Where the ground at the post is higher than the road, the box sits lower above that ground; where it is lower, higher. Measure the difference with a level from the road’s edge.
The post: one that gives way
USPS passes on the Federal Highway Administration’s advice: a 4″ × 4″ wooden post or a 2″-diameter steel or aluminum pipe, which bends or falls if a car hits it, buried no more than 24″. Never a concrete post, heavy pipe or a milk can filled with concrete.
Door slots and wall boxes
A door slot’s opening must be at least 1½″ × 7″, with its bottom at least 30″ above the floor. A wall mailbox replaces a curbside one only with your local postmaster’s permission, near the main entrance; USPS sets no height for it.
House numbers you can read from the street
The building code (IRC R319.1) asks for address numbers at least 4″ tall with a ½″ stroke, legible from the street. For a house set farther back, the ADA’s sign table (703.5.5) gives a size for any distance: for characters beside a door, 2″ plus ⅛″ for every foot past 15′. The numbers on the box itself: 5/8″ plus ⅛″ a foot past 6′, read from across a two-lane road, 24′, is 3″.
Mailbox height chart
| Ground at the post | Box bottom above the ground | Post, 24″ buried |
|---|---|---|
| 6″ below the road | 47–51″ | 73″ long |
| Level with the road | 41–45″ | 67″ long |
| 4″ above the road | 37–41″ | 63″ long |
| 8″ above the road | 33–37″ | 59″ long |
The post lengths put the box’s bottom at 43″ from the road, the middle of the USPS range, with the box sitting on the post’s top.
House number size by distance
| From the street | Numbers at least | Buy |
|---|---|---|
| 30 ft | 4″ | 4″ |
| 40 ft | 5⅛″ | 6″ |
| 60 ft | 7⅝″ | 8″ |
| 80 ft | 10⅛″ | 12″ |
| 100 ft | 12⅝″ | 16″ |
Three worked examples
A curb and level ground. Put the box’s bottom 41–45″ above the road, aiming for 43″, its front 6–8″ behind the curb, on a 67″ post with 24″ in the ground. From 40 ft, the house numbers should be 6″.
A lawn 6″ above the road. The rule starts at the road, so above the lawn the box’s bottom goes 35–39″ up, and the post is 61″ long.
A door slot, the house 60 ft back. The slot’s bottom at least 30″ above the floor, its opening at least 1½″ × 7″, and house numbers 8″ tall to read from the street.
Common mailbox mistakes
- Measuring from the grass. The USPS height starts at the road surface. On a raised lawn, a box set 43″ above the grass is too high for the carrier.
- Setting it flush with the curb. The front of the box goes 6–8″ back, or passing cars and snowplows clip it.
- A post that will not give. Brick pillars, concrete and heavy pipe turn a fender-bender into a serious crash. A 4×4 or a 2″ pipe bends.
- Burying the post too deep. USPS and the Federal Highway Administration say 24″ at most, so it can still give way.
- Small or low-contrast numbers. Emergency crews look for them at night. Use 4″ or taller, in a color that stands out from the wall.
Working on the front of the house? See how it scores in Rate My Curb Appeal, try new colors in the exterior house color visualizer, or plan a room in the free 2D room planner.
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Mailbox height questions
What is the standard mailbox height?
41–45″ from the road surface to the bottom of the mailbox, or to the point where the mail goes in, as USPS asks. Most people aim for the middle, 43″.
What are the mailbox height requirements?
USPS asks for the box’s bottom 41–45″ above the road and its front 6–8″ back from the curb, with your house number on the box. Your local postmaster decides where there is no raised curb.
How high should a mailbox be from the ground?
It depends on the ground: the rule is measured from the road. On ground level with the road, 41–45″. Where the ground at the post is 6″ higher than the road, 35–39″ above that ground.
How far from the curb should a mailbox be?
USPS asks for 6–8″ back from the curb to the front of the box. Without a raised curb, ask your local postmaster.
How deep should a mailbox post be?
No more than 24″, as USPS and the Federal Highway Administration advise, in a 4″ × 4″ wood post or a 2″ steel or aluminum pipe, so the post gives way if a car hits it.
How big should house numbers be?
At least 4″ tall with a ½″ stroke, by the building code (IRC R319.1). For a house far from the street, go bigger: about 6″ at 40 ft and 8″ at 60 ft, by the ADA’s sign table.