A toilet’s rough opening is the space from the wall to the center of the drain, and it should include clearance for the tank lid. The information that comes with a new toilet will tell you its rough opening requirements. If you don’t have the information, or if you need to measure the existing plumbing’s rough opening, you only need a measuring tape or ruler. In newer homes, the rough opening for a standard toilet is usually 12 inches. An older home or non-standard, contemporary toilet might require you to move the drain to take the measurement.
Things You'll Need
- Ruler or measuring tape
Place the lid on the toilet tank.
Move the toilet against a wall, leaving an inch of space between the back edge of the lid and the wall.
Measure from the bolt opening on one side of the base of the toilet to the wall, accounting for the thickness of the baseboard, if necessary.
Tips & Warnings
- The rough opening for a toilet that is already installed is measured the same way -- from the floor bolts to the wall.
- If no toilet is installed, measure from the wall to the center of the floor drain.
- Toilets are usually porcelain and can crack with rough handling.
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