Make sure you'll still have plenty of space. When you replace a tub with a shower, the toilet can start to feel crowded. Make sure you pay attention to this so it feels right to you. Try to keep at least 15 inches room from the center of the toilet to the new shower glass. If your shower ends up being on the smaller side, you can skimp on this measurement a bit.Tip: Hold up a sheet of scrap drywall to act as a fake glass panel and sit on a 5-gallon bucket to mimic the toilet's location. This can help you decide how close you like the glass, and how big you'd like your shower.Stand in the place where your shower will be. A shower depth of 32 inches feels small to me, but might work for you. A depth of 34 to 36 inches tends to be ideal, but again, don't crowd the toilet. Make sure you check your local code for minimum distances, too.