A 48-inch vanity is approximately 122 cm wide. A 100 or 105 cm-wide mirror is a useful starting point if you want visible space beside it; a 120 cm mirror creates an almost full-width look. None is a universal rule. Side lights, basin position and usable wall space should decide the final fit.
Measure the vanity itself rather than relying on its advertised inch size. Mark the mirror outline above it, then stand at the basin. The right width should give a comfortable reflection and a deliberate relationship with the furniture.
Compare the width in centimetres
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| Mirror width | Centred on a 122 cm vanity | Visual effect |
|---|---|---|
| 100 cm | About 11 cm of vanity width beyond each side | A generous reflection with room around it. |
| 105 cm | About 8.5 cm beyond each side | A fuller look without reaching the furniture edges. |
| 120 cm | About 1 cm beyond each side | Near full width; measure the wall and fittings carefully. |
These are simple design calculations, not required installation clearances. Enter 121.9 cm in the mirror size calculator and compare its suggestion with the real layout. A light fitting or cupboard may make a smaller mirror more practical.
100 × 60 cm: a balanced rectangular option
100 × 60 cm dual-light mirror — £198. A broad reflection for the basin with front and rear illumination, dimming, three light colours and anti-fog. Choose it when you want space beside the mirror rather than filling the wall edge to edge.
105 × 50 cm: wider, with less height
105 × 50 cm dual-light mirror — £228. This proportion can suit a lower vertical gap while maintaining width. Check that the 50 cm height gives the users a comfortable reflection above the tap; do not select it by width alone.
80 cm round: a softer focal point
80 cm round backlit mirror — £179. A circle leaves more open wall beside a 122 cm vanity and softens straight furniture lines. Its rear glow is atmospheric; include useful face lighting elsewhere if makeup is a priority.
Prices and stock checked on 27 October 2026. Listed prices are before any checkout promotion.
Shape changes the apparent size
A circle narrows above and below its widest point, while a rectangle fills its full outline. Compare round LED mirrors, rectangular LED mirrors and oval illuminated mirrors using width and height together. An irregular mirror can add character where the rest of the room is simple.
For an unlit alternative, see the frameless bevelled round mirror. The black-framed rope design offers another styling reference; allow for its complete hanging arrangement, not just the glass diameter.
Finish the layout around your routine
Place the reflection where the household can use it comfortably. Include taps, splashback, controls and nearby lights in the outline test. An oval anti-fog design may suit a narrower basin position, while dressing-table makeup mirrors solve a different need away from the bathroom.
If you prefer almost full-width coverage, the 120 × 60 cm dual-light version — £249 is another option to measure. Leave the space required by its mounting method and surrounding fittings rather than assuming a nominal 122 cm wall is enough.