This depends on the size of your bathtub and how much area you want to cover. For a younger baby that’s just sitting up, a smaller bath mat is fine because they’re not moving around the tub. Once your baby gets a little more mobile, you may want something that covers the majority of the tub bottom. Your best bet is to measure your tub and make sure that you don’t get one that’s too long. If it is, it won’t be able to suction properly and won’t be as safe.