A bathroom mirror usually looks balanced when it is no wider than the vanity, with some visible wall or furniture margin on each side. That is a design starting point, not a fixed installation rule. The best width also depends on the basin position, side lights and the reflection you want.
Begin with the vanity width in centimetres. Subtract the space needed for side lights or cabinets, then compare actual mirror dimensions. A tape outline on the wall makes the choice much easier to judge before you order.
A practical size shortlist
On a small screen, swipe the table to compare all columns.
| Vanity layout | Mirror sizes to compare | What to check |
|---|---|---|
| About 50–60 cm wide | 40–50 cm mirror width | Tap clearance and a useful reflection in a compact room. |
| About 80–100 cm wide | 60–80 cm mirror width | Basin centring and room for side lights. |
| About 140–160 cm wide | One broad mirror or two smaller mirrors | Basin centres, shared viewing area and the gap between separate mirrors. |
These are starting points for shopping rather than guaranteed fits. For a tailored estimate, use the mirror size calculator with your furniture measurements. Browse small bathroom mirrors for compact layouts or large bathroom mirrors for wider furniture.
Three sizes, three different vanity layouts
40 × 50 cm frontlit anti-fog mirror — £89. On a 60 cm vanity, a 40 cm-wide mirror leaves a nominal 10 cm margin on each side when centred. That arithmetic is useful for a first outline; check taps, shelves and any lighting fittings before settling on it.
80 cm round backlit mirror — £179. A softer outline for a wider single vanity. On a 100 cm unit, the diameter leaves a nominal 10 cm margin on each side. A circle narrows towards its top and bottom, so judge the usable reflection as well as the outside diameter. Compare round LED mirrors if you like this shape.
140 × 70 cm extra-large LED mirror — £299. A broad, continuous reflection for wider furniture or a shared vanity. Front and back lighting, dimming and anti-fog help make the space practical for two routines. Measure the usable wall width, not just the worktop.
Prices and stock checked on 27 October 2026. Listed prices are before any checkout promotion.
Height: fit the reflection to the people using it
Position the lower edge clear of taps, splashback and fittings while keeping a comfortable view for regular users. There is no universal gap above every tap: a tall mixer, a raised basin and a low ceiling change the available space. Check the shortest and tallest users before the installer marks the brackets.
Leave access to touch controls and room for the specified mounting arrangement. If the mirror has a frame, use the overall dimensions for clearance and the glass area for the view. Our bathroom mirror cleaning guide helps keep that reflection clear after installation.
One wide mirror or two separate mirrors?
Choose one wide mirror for a continuous reflection and a simple focal point. Choose two smaller mirrors when you want each basin to have its own defined place. With a pair, mark both basin centres and leave a deliberate gap between the mirrors; do not split the overall vanity width in half and assume everything will fit.
Front lighting is useful for makeup and shaving. Backlighting creates a glow around the wall. A dual-light design combines both effects. Select the right light direction alongside the size, so the room looks good and works well during busy mornings.
Size questions
Can the mirror be the same width as the vanity?
Yes, that can create a deliberate fitted look if the wall, fittings and mounting clearances suit it. A narrower mirror is often easier to balance with side lighting.
Must a mirror never extend beyond the vanity?
No absolute style rule applies to every room. A wider mirror can be intentional, but check the wall layout and adjacent furniture carefully rather than assuming bigger is always better.
For more specific layouts, read cloakroom mirror sizing, mirrors for an 800 mm vanity and matching mirror and vanity widths. Find your preferred shape and lighting at LED Mirror World.