One may not think to "try on" a toilet before purchasing, but it is a good idea to make sure it is a good size for everyone in the household. No one wants to install a toilet just to find out that it is too short for the taller users, or hard for older people to get up from. With the thickness of the seat included, the standard height of the toilet is 16-17 inches. They are available in taller models in case anyone in the home is extremely tall. Most standard bowls are round, but elongated bowls are an option. If the space is limited, an elongated bowl may not be the best choice, as it would take up leg room. Make sure the drain and the water hook ups line up in size with what is already there. Additionally, factor in the placement of other items in your bathroom. You wouldn't want your knees to be bumping into your bathroom vanity cabinet, for example.