A group of four extra-large rural mailboxes supported by two oversized 4 x 6 posts and brackets.

Rural mailboxes, approved by the U.S. Postmaster General, are available in 3 basic sizes, by several different names each:

• # 1 or T1 or "standard" is the smallest and the most common size
  • approximate dimensions are 19" long x 7" wide x 9" high
• # 1-1/2 or T2 or "oversized" is the next largest size
  • approximate dimensions are 20" long x 8.5" wide x 11" high
• # 2 or T3 or "extra-large" is the largest standardized mailbox
  • approximate dimensions are 22" long x 10.5" wide x 14" high

Like many things in residential construction, the most common product size is usually the least expensive initial purchase, but it may not be the best choice in the long run — the cost of the gas you burn driving to and from the local post office to pick up your slightly oversized packages could quickly erase any savings you might have enjoyed buying that little "standard" sized mailbox.