To evenly illuminate a bathroom mirror from either side, we recommend mounting your sconce(s) just above eye level, or about 60"- 65" from the floor to the center height of the sconce backplate.
Bath Sconce Tip #2
When installing above the mirror, the ideal linear bath light will measure at least 3/4 the width of the mirror but not extend over its edges. For larger mirrors, consider mounting a pair of evenly-spaced linear sconces.