Bathroom Mirror Size Calculator — Width, Height & Mounting Guide
Enter your vanity width, standing eye height and countertop height to get the recommended mirror width, height and exact mounting position — both in centimetres and inches.
cm
cm
cm
75% of vanity width — balanced with the sink unit
- 1
Mirror top edge
165 cm + 5 cm = 170 cm - 2
Mirror bottom edge
85 cm + 5 cm = 90 cm - 3
Mirror height
170 − 90 cm = 80 cm - 4
Mirror width
90 cm × 75% = 6875% of vanity width is the standard interior-design guideline.
How does this calculator work?
Mirror width ≈ 75% of vanity width. Height = from 5 cm above countertop to 5 cm above eye level. Mount the bracket at the midpoint (the mirror centre height). For a 90 cm vanity with 165 cm eye height and 85 cm countertop, that gives roughly a 68 cm wide × 80 cm tall mirror, centre at ~130 cm from the floor.
Formula
How this is calculated
Interior designers follow two core rules for bathroom mirrors: (1) the mirror should be narrower than the vanity — typically 70–80% of the cabinet width — so it looks centred and balanced rather than oversized; and (2) the mirror should frame the face correctly, with the top edge roughly 5 cm above your eye level so you can see the top of your head, and the bottom edge just above the countertop with a small gap (about 5 cm) to protect it from splash damage.
These rules are starting points, not absolutes. Taller users may want the mirror centre higher; if multiple people of different heights share the basin, position the centre at the average eye height. For double-sink vanities, two separate mirrors often look better than one very wide mirror.
The mounting centre height is where you fix the bracket or wall anchor. Standard bathroom mirror sizes in UK/EU are often 60 × 80 cm, 70 × 90 cm or 80 × 100 cm — pick the nearest standard size to the calculated recommendation, rounding the width down to stay narrower than the vanity.
Frequently asked questions
A common guideline is 70–80% of the vanity width. A 90 cm vanity suits a 60–70 cm wide mirror. Going narrower keeps the look clean; going wider than the vanity (or the same width) can make the room feel cluttered. Leave at least 5–10 cm of wall visible on each side.
Position the mirror so the top edge is 5–10 cm above your eye level (so you can see your hair) and the bottom edge is 5–10 cm above the countertop. For the average adult standing at 165 cm eye height and an 85 cm countertop, the centre of the mirror falls around 130 cm from the floor.
Yes, many homeowners use a single mirror spanning the full double vanity. In that case, aim for roughly 90–95% of the vanity width to minimise the side gaps while keeping it slightly inset. Alternatively, two matching mirrors — one per sink — are equally popular and easier to hang level.
TG we-Calculate Editorial Team. (2026). Bathroom Mirror Size Calculator — Width, Height & Mounting Guide [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/bathroom-mirror-size-calculator
TG we-Calculate Editorial Team. "Bathroom Mirror Size Calculator — Width, Height & Mounting Guide." TG we-Calculate. 2026. https://we-calculate.com/calculator/bathroom-mirror-size-calculator.
TG we-Calculate Editorial Team, "Bathroom Mirror Size Calculator — Width, Height & Mounting Guide," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/bathroom-mirror-size-calculator
@misc{wecalculate_bathroom_mirror_size_calculator, title = {Bathroom Mirror Size Calculator — Width, Height & Mounting Guide}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/bathroom-mirror-size-calculator}}, year = {2026}, note = {TG we-Calculate} }
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