Size your mirror
Where it goes and what sits below it.
How this calculator works
- Vanity: width = furniture width − 4 in, minimum 18. Height 36 in. Bottom edge = counter top + 8 in.
- Console: width = 70% of furniture width, rounded, minimum 18. Height 36 in, bottom edge 8 in above the top.
- Full length: bottom edge at 6 in from the floor, top edge at the user's height in inches plus 4, giving a height of at least 60 in. Width 24 in.
- Feature wall: width = 60% of the wall, height = 55% of the ceiling height, centred vertically on the wall.
- A round mirror takes the smaller of the computed width and height as its diameter.
- Weight = area in m² × thickness in mm × 2.5 kg, the standard density figure for float glass.
| Position | Width rule | Height | Bottom edge | Clear space in front |
|---|---|---|---|---|
| Over a vanity | Counter width − 4 in | 36 in | Counter + 8 in | 24 in |
| Over a console | 70% of console width | 36 in | Console top + 8 in | 24 in |
| Full length | 24 in, 30 for two users | User height + 4 in, less 6 | 6 in from floor | 36 in |
| Feature wall | 60% of wall width | 55% of ceiling height | Centred on the wall | Depends on the room |
| 5 mm float glass | — | — | — | 12.5 kg per m² |
| 6 mm float glass | — | — | — | 15 kg per m² |
Design and build under one accountable roof
Worked example — over a 64-inch vanity
| Step | Arithmetic | Result |
|---|---|---|
| Mirror width | 64 − 4 | 60 in |
| Mirror height | standard | 36 in |
| Bottom edge | 34 counter + 8 | 42 in from floor |
| Top edge | 42 + 36 | 78 in from floor |
| Ceiling check | 120 − 78 | 42 in of wall above — comfortable |
| Area | 60 × 36 ÷ 144 × 0.0929 | 1.39 m² |
| Weight at 5 mm | 1.39 × 5 × 2.5 | 17.4 kg |
Hanging and fixing a mirror that stays up
A 17-kilogram mirror held on adhesive alone is a mirror that will come off a wall at some point in the next ten years, usually in a bathroom where the adhesive has been working against steam the whole time. The correct fixing is both: mirror adhesive for the bond, and a mechanical element — clips at the corners, or a J-channel under the bottom edge — carrying the weight. In a drywall, a plywood backing plate must go in before boarding; nothing else in a gypsum partition will reliably hold a large mirror.
In a bathroom, also specify a mirror with a protected backing. Ordinary silvered glass in a Mumbai bathroom develops black edge spotting within three or four years as moisture reaches the silver at the cut edges. A copper-free mirror with a sealed edge costs about 20% more and does not do it. If the mirror is going into a humid bathroom with no exhaust, the extra cost is not optional.
On lighting, the rule is simple and widely ignored: light the face, not the mirror. Two vertical fittings at either side of the mirror at about eye height produce even, shadow-free light on a face. A downlight above the mirror puts the eye sockets, the nose and the chin into shadow, which is why bathroom selfies under one are unflattering and why shaving and make-up are harder than they need to be.
Every constant on this page comes from Greenbox site records — measured drawings, signed BOQs and completion certificates from projects delivered between 2023 and 2026 — rounded to the figures an estimator would actually write down. We publish them so the arithmetic can be audited rather than trusted. Treat the output as a planning figure: accurate enough to brief a landlord, a bank or a family, and not accurate enough to sign a contract against.
What this tool does not cover
- Frames, bevels and LED-backlit mirror units, all of which change the overall size and the fixing.
- Mirror cabinets, which are 4 to 6 inches deep and project into the standing space.
- Demisters and heated pads, which need a fused connection behind the mirror decided before tiling.
- Safety backing film, which should be specified on any mirror over about 1.5 m² or in a child's room.
- Cutting and edge polishing, which is charged per running foot.
- For the vanity below, see the bathroom vanity size calculator.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
What size mirror over a 60-inch vanity?+
About 56 inches wide and 36 tall, with the bottom edge 8 inches above the counter. The mirror should be at least as wide as the basin and ideally close to the full counter width, leaving a couple of inches of tile visible at each side.
How high should a bathroom mirror be hung?+
Bottom edge about 8 inches above the counter, which for a standard 34-inch vanity puts it at 42 inches from the floor. The centre of the mirror should sit at roughly the eye level of the people using it, which a 36-inch-tall mirror accommodates easily.
What size should a full-length mirror be?+
At least 60 inches tall, with the top edge 4 inches above the tallest user's height and the bottom edge about 6 inches off the floor. Twenty-four inches wide is the practical minimum and 30 is better if two people use it. It also needs 36 inches of clear floor in front to be useful.
How do you fix a heavy mirror to a wall?+
Mirror adhesive for the bond plus a mechanical element — corner clips or a J-channel under the bottom edge — to carry the weight. Adhesive alone eventually fails, particularly in a bathroom. In a drywall, a plywood backing plate must go in before the board.
Why do bathroom mirrors develop black edges?+
Moisture reaching the silver layer at the cut edge. Ordinary silvered glass in a humid Mumbai bathroom shows it within three or four years. A copper-free mirror with a sealed edge costs about 20% more and does not, which makes it the obvious specification in any bathroom without good extraction.