The installation height for medicine cabinets is generally accepted to be 64 inches from the floor to the mirror's center, according to Broan.
Consider Specific Family Traits
Install a medicine cabinet at a height that is accessible to everyone in your family without anyone having to strain to look in the mirror. If you have small children, you may want to install it higher up to avoid unintended exploration.
Mark the measurements for the medicine cabinet assuming a standard 64-inch height. Examine the measurements to ensure accessibility for all family members. Make any adjustments according to personal preference or need.