The majority of round cribs are designed to fit a mattress 42 inches in diameter. The total diameter of the crib frame is usually 46 inches.
Some round cribs also have canopy posts that may extend beyond the 46-inch diameter.
It is very difficult to find a round crib without tall posts, which means that the total height is about 76 inches. The rails of the crib are usually at about the same height as a traditional crib, somewhere between 3 and 4 feet above the ground.
The mattress of a standard round crib measures 42 inches in diameter and 5 inches tall. It is usually included in the price of the round crib and is made of firm foam.
Specialty bedding is required with round cribs because crib sheets must fit snugly for safety reasons. Most companies that sell round cribs also sell bedding sets with sheets to fit the 42-inch round mattress.
Although round cribs are a beautiful addition to a nursery, they will not be able to be used as long as rectangular crib mattresses. Children will outgrow a round crib at about 35 inches tall, usually around 2 1/2 years old.