You must take into account the existing height of the piece when you install one in your bathroom.
How high to hang a wall mounted bathroom vanity.
Place the light about 40 inches above the top of your vanity.
For a 36 inch high countertop make a second mark 34 inches above the floor to represent the top of the 2x6 brace.
You can also use the vanity as a guide.
Measure 3 inches from the top of the mirror or 7 feet vertically from the floor if the mirror is not already in place.
Mark the vanity s width above the rough plumbing.
Draw a second line 5 inches lower for the bottom of the brace.
Extend the mark with a level.
Mark with a pencil to indicate the bottom edge of the light.
Wall hung vanities come in multiple sizes depending on the manufacturer.
If the piece measures 20 inches high and you want a height of 31 inches you must mount it 11 inches above the floor.
Install the light above the medicine cabinet or mirror at a height of about 75 to 80 inches from the floor.