The deck, or running surface, can vary slightly from the most common size of 20 x 55 depending on the quality and needs of the user. If you are tall or run fast, you may want to look for a deck length of 60â€ or maybe even 62.
Some decks can be shorter, as short as 50, but while this may make storage easier, it can make walking more difficult. While 20 is the most common deck width, you may be able to find one with a width of 22. Anything 18 or less gives you less room to run since you will likely move left and right slightly during exercise but it can be beneficial if you don't have a lot of room.