The standard height for a curbside mailbox is 41 to 45 inches above the ground, according to the U.S. Postal Service. For locations that have raised curbs, the box sits 6 to 8 inches away from the curb.
The local postmaster provides regulations for mailbox placement at addresses that do not have raised curbs. Recommended mailbox supports include 4-inch by 4-inch wooden posts and aluminum or steel posts that are 2 inches in diameter. The post should sink up to 24 inches into the ground. A concrete post is not recommended, because the post needs to yield if a car collides with it. The mailbox should include the house or apartment number.