As a general rule, a vanity mirror should measure several inches fewer than your vanity sink area. For example a 30 in. wide vanity should be paired with a 26-28 in. wide mirror.Feb 6, 2020
Typically, the mirror should not be wider than the sink or vanity. ... It would look odd, for example, if a small mirror were flush against the sink with a huge expanse of wall space above. Basically, the mirror shouldn't be conspicuously far above the sink nor, unless it is a very large mirror, too close to the sink.Sep 6, 2012
What size mirror do I need?
What size mirror should I get? A good rule of thumb (or eye) is to choose a mirror that's around two thirds of the size of the furniture it's hanging above.