You will find many manufacturers who are kind enough to provide more than just one size. This gives you the chance of choices based on your personal preference. Another good thing is, almost all of the sizes will fit into a standard bathtub space, in case if you are not sure about the space of your bathroom. You might know that space for a standard bathtub is usually about 60 inches long and 30 to 32 inches wide. You can purchase a walk-in tub that is bigger than a standard tub and also tubs that are small enough to fit into a shower stall. The majority of walk-in bathtubs are a bit deeper than a standard bathtub. Some walk in bathtubs are designed so that they can be sealed into the area similar to a standard tub.