A bathroom mirror should fit the usable vanity wall and give everyone a comfortable reflection. For a single basin, a mirror slightly narrower than the vanity often looks balanced, but there is no universal width or mounting height. Start with the vanity, taps, wall lights and people who use the room, then test the outline before ordering.
Measure the actual space
Record the vanity width and the clear wall area, including any return wall, sloped ceiling, shelf or fitting. Measure the top of the tap and allow working space around it. A basin’s bowl width and the full vanity width are different measurements; use both to understand the composition.
If you are choosing a smaller design, compare compact bathroom mirrors by exact width and height. For a wide unit, use the large mirror range alongside your clear-wall measurement.
Test three real dimensions on the wall
40 × 50 cm compact LED mirror — £89. Start with a paper rectangle this size if a narrow basin wall is the constraint. Check the usable reflection from your normal standing position.
60 × 80 cm double-light mirror — £129. Compare the taller outline with taps, shelves and the users’ eye levels. Confirm the intended mounting orientation before marking fixing points.
140 × 70 cm extra-large double-light mirror — £299. A broad option for a wider vanity wall. It needs sufficient clear width and a suitable mounting plan; being large does not automatically make it the right fit.
Prices and stock checked on 27 October 2026. Listed prices are before any checkout promotion.
One basin or two?
For a single basin, centre the useful reflection around the basin and regular user. Leaving some wall visible on each side can frame the mirror nicely, but the amount depends on the composition and adjacent lights.
For two basins, compare a continuous wide mirror with two individual mirrors. One larger reflection can connect the space; two mirrors can align with separate basin positions. Do not select a fixed width solely because the vanity is described as “double”.
Our guides to mirror width compared with the sink and mirrors for a 48-inch vanity explore those proportions. The mirror size calculator gives a starting estimate to compare with the actual wall.
Set height for the people using it
Stand at the basin and check the shortest and tallest regular users. Place a paper outline so both can see comfortably without bending or standing on tiptoe. Include the space above the tap and any overhead light. A single floor-to-centre rule cannot suit all users and layouts.
For more detail, see mirror height over a bathroom sink and planning mirror dimensions.
Shape changes the outline and reflection
A rectangle gives a structured viewing area, while round and oval mirrors soften the edges. A circle’s widest point is its diameter; the usable width narrows towards its top and bottom, so do not compare it as though it were a square of the same width.
Explore square and arched designs for other outlines. The oval backlit model shows how a taller curve can fit above a narrower basin.
Leave room for the installation
A framed mirror, a backlit mirror and a cabinet can project different distances from the wall. Include mounting clearances, rear lighting space and any door swing. Use the product’s mounting requirements and have a qualified electrician complete hardwired bathroom connections.
If replacing a bonded mirror, plan adhesive removal and wall preparation before assuming the new unit can cover the same fixing area. Our wall fixing guide covers mounting considerations.
Balance size with the finished look
A well-chosen mirror gives you a comfortable reflection and a deliberate-looking vanity. It need not fill every available centimetre. Use styling around a larger mirror and statement mirror ideas once you have checked the practical fit.