Bathroom Mirror Size Calculator
Enter your vanity width and your height to get a recommended mirror size and mounting height.
What this calculator does
The Bathroom Mirror Size Calculator recommends a mirror width based on your vanity size, plus a mounting height so the mirror is centered comfortably at your eye level.
How the calculation works
A common design rule of thumb is to make the mirror about 2 inches narrower than the vanity on each side (4 inches narrower total), which leaves a clean visual margin. For mounting height, eye level is estimated as roughly 93% of a standing adult’s height, and the mirror is centered on that point by placing its bottom edge half the mirror’s height below eye level.
This tool gives general design guidance for planning purposes. Actual placement should also account for your specific fixtures, lighting, and any accessibility needs in the bathroom.