A mirror that is too wide crowds the lights; too narrow and it looks lost. Enter your vanity width and the wall space above it, and get a mirror size in balance with both.
Bathroom Mirror Size Calculator
How this calculator works
Mirrors look right when they sit slightly inside the vanity’s edges — an inch or two of clearance on each side — and leave breathing room under the light fixture. For a double vanity you can hang one mirror over each sink, centred on the taps, which usually looks sharper than one long sheet. Keep the bottom edge a hand’s width above the backsplash so splashes and taps stay easy to clean.
Good to know
A common guide is to make the mirror about 2 to 4 inches narrower than the vanity so each side keeps a little breathing room and lights do not crowd the frame. Keep the mirror centred over the sink, not just over the cabinet, especially on offset basins.
For height, a mirror centre around 57 to 60 inches from the floor suits most households, with the bottom a few inches above the taps so splashes stay off the edge. Leave space below wall lights and above the backsplash so the frame does not touch either.
Frequently asked questions
Can my mirror be wider than the vanity? Best keep it at or just inside the vanity edges. A mirror that overhangs looks top-heavy and can clash with lights and walls; if you want a larger look, use a taller mirror instead of a wider one.
Two mirrors or one wide mirror? Two mirrors centred over each sink usually look tidier on a double vanity, while one wide mirror reflects more light and suits a single long counter. Leave a small gap between two mirrors so cleaning and alignment stay easy.
What is the best mirror height? Hang it so the centre sits near eye level, roughly 57 to 60 inches up, and check that taller and shorter users can both see their full face with a small margin above the head.
How do I measure for a round mirror? Use its diameter in place of width and centre the circle over the sink. Keep the widest part inside the vanity width and leave the same side clearances as you would for a rectangle.