The United States Postal Service requires mailboxes to be at a height of 41 to 45 inches. The mailbox should be measured from the road surface to the bottom of the mailbox. In addition, the mailbox door should sit back 6 to 8 inches from the edge of the road.
USPS Regulation Height.
Special Circumstances Considered.
Special circumstances may apply if your road or curb prevents you from meeting the requirements set forth by the USPS. If you fall into this category, contact your local USPS postmaster to discuss options.
In nearly all situations, the USPS requires mailboxes to be between 41 and 45 inches from the ground. If your road or curb does not permit this, contact your local postmaster.