Make sure that your new toilet will fit in place of the old one. Measure from the wall behind the toilet to the center of one of the closet bolts (the bolts that hold the toilet down). Do this before you remove the old toilet so you can buy your new one and have it on hand before you start. If the toilet has four closet bolts, measure to the center of one of the rear ones. Also, measure from the center of the mounting holes to the back of the new toilet you’re considering. Compare these two measurements. If the base of the new toilet is shorter than the distance between the rear bolt holes and the wall, it should fit. In small bathrooms where space is tight, also measure from the sides of the flange bolts to sidewalls or other objects to assure side-to-side clearance. You don’t want to find that you can’t wedge your new toilet into place because it’s trying to occupy some of the same space as your vanity.