Bathroom mirror size calculator

The trade sizes it to the basin or the vanity it sits above, not to the wall: about the width of the basin, stopping 50mm short either side so the edge reads as deliberate rather than nearly-flush. In height it starts 150mm or so above the basin or the tap, so splashes do not sit on the silvering, and stops 100mm below the ceiling or the light. The calculator applies exactly that and prints the arithmetic.

So that the standing eye line falls inside the glass. Adult eye height is typically 1500mm to 1750mm off the floor, so the glass should cover that band with room to spare; a mirror that starts above a basin at worktop height and is 900mm or more tall does so on its own.

Usually no. A mirror wider than the basin or vanity looks as if it was cut for a different room; a mirror the same width looks like a mistake in the fitting. Slightly narrower, with an even margin either side, is what the eye reads as intended. Over a double vanity the same rule gives one wide mirror or two, each sized to its own basin.

4mm silvered mirror up to about a metre on the longest edge and 6mm over that, from the same table our thickness tool applies. Thin mirror bows on a large face and the reflection swims; the extra millimetres keep it flat. Mirror is not toughened.

Yes, and they have to be drilled before the edges are worked, so decide the fixing before you order: screw holes with caps, adhesive, or a hanging system. A finished mirror cannot be drilled afterwards without cracking it or lifting the silvering.