A bathroom mirror should work with the vanity, tapware and lighting as one resolved area. This bathroom mirror sizing guide covers the dimensions that matter most, so the finished wall feels balanced and useful every day. The right size is rarely about filling every available space. It is about matching the mirror to the layout in front of it.
For most bathrooms, the vanity width is the best place to start. From there, check the basin position, wall lights, ceiling height and whether the room needs storage behind the glass. A custom mirror gives you more flexibility where standard sizes leave awkward gaps or do not suit the wall.
Start with the vanity width
A mirror is usually narrower than the vanity, or close to the same width. This creates a clean visual line and keeps the mirror connected to the joinery below it.
As a practical rule, allow the mirror to sit 50 mm to 150 mm in from each side of the vanity. For example, an 800 mm vanity often suits a mirror between 600 mm and 750 mm wide. A 1200 mm double vanity may suit one wide mirror around 1000 mm to 1100 mm, or two separate mirrors aligned with each basin.
There are exceptions. A full-width mirror can look sharp over a floating vanity when the wall is simple and the tapware position is centred. A narrower mirror can also be the better choice where a wall light, tall shaving cabinet or side return limits the available space. The aim is not to follow a fixed formula. It is to leave intentional, even margins.
Avoid selecting a mirror only by the size of the empty wall. A mirror that extends far beyond the vanity can make the basin zone feel disconnected, particularly in a compact ensuite. Conversely, a small mirror over a broad vanity can leave the wall looking underdone.
Bathroom mirror sizing guide: choose the right height
Mirror height comes down to who will use the bathroom, the ceiling line and what sits above the vanity. A common wall mirror height is 700 mm to 1000 mm, though a custom-cut piece can suit nearly any proportion.
The bottom edge generally sits 100 mm to 200 mm above the vanity top or splashback. This gap gives the mirror room to breathe and makes cleaning around the basin easier. If the vanity has an above-counter basin, measure from the bench rather than the top of the bowl.
For the top edge, make sure the mirror serves its purpose before worrying about symmetry. It should allow a clear reflection for regular grooming without forcing a very tall installation. In bathrooms with high ceilings, an oversized mirror can make the wall feel vertical and empty rather than refined. A well-proportioned height often looks better than taking the glass all the way towards the ceiling.
A taller mirror is useful where natural light is limited, as it can help distribute light around the room. It also works well over a low-profile vanity. In a bathroom with wall-mounted lights above the mirror, leave enough space for the fitting and its light spread. The mirror and lighting need to be specified together, not as separate decisions.
Set the mirror around the basin, not just the wall
A centred basin should usually have a centred mirror. This is the simplest way to create a calm, ordered result.
With an offset basin, there are two valid approaches. Centre the mirror to the vanity for a more architectural look, or centre it to the basin for a more functional focal point. The better option depends on nearby features such as a tall cabinet, window or shower screen. Marking the proposed mirror edges with painter's tape is an easy way to check the balance before finalising the size.
For double basins, separate mirrors can define each position neatly. Leave a consistent gap between them and line up their top and bottom edges. One wide mirror is often the cleaner option when the vanity is long, the wall is uninterrupted and the tapware is evenly spaced.
Round, arched or rectangular mirrors
The shape changes how a mirror occupies the wall, even when the overall dimensions are similar.
A rectangular mirror is the most adaptable option. It suits narrow vanities, double vanities and bathrooms with straight-lined joinery. It can be installed vertically to add height, or horizontally to follow a wide vanity. For a modern fit-out, square corners give a crisp finish, while softened corners can reduce the hardness of a compact room.
Round mirrors suit a single basin particularly well. Their diameter should still relate to the vanity width. As a guide, a 600 mm to 800 mm round mirror often works over an 800 mm to 1000 mm vanity. Going too small can make the mirror look like an accessory rather than a working part of the bathroom.
Arched mirrors introduce height and a softer profile. They need enough clear wall above them to show the shape properly. If an arch is squeezed beneath a light fitting or ceiling bulkhead, the effect is lost. Use the overall height, not only the straight-sided section, when checking your measurements.
Plan for lights, power points and storage
Bathroom mirrors do not sit alone. Wall lights, pendants, power points, exhaust controls and shaving cabinets all affect the final size and position.
If lights are mounted on either side of the mirror, allow clear, equal spacing. Side lighting can be very effective, but it takes up wall width. A mirror that would otherwise suit the vanity may need to be reduced to accommodate the fittings without crowding the area.
For an overhead light, consider the mounting height, fitting projection and where the beam lands. The goal is useful light at the mirror, not a fitting pressed too close to the glass. Confirm electrical locations early, before manufacturing begins.
A shaving cabinet adds storage but needs practical clearance. Check how far the door opens, where it will sit in relation to the tapware, and whether it changes the visual centre of the vanity. A recessed cabinet can keep the profile neat, but the wall construction needs to allow for it. A surface-mounted cabinet is more straightforward where recessing is not possible.
Measure the finished space, not the plan
Plans are useful for layout decisions, but final mirror measurements should be taken after wall linings, tiles, vanity installation and electrical rough-in are complete. Small changes in tile set-out, wall thickness or vanity placement can alter the usable opening.
Measure the width in more than one place where the mirror will sit. Check the distance from the vanity top to lights, ceiling features and any side wall or cabinet. Also confirm whether the mirror needs cut-outs, edge details or clearance around fittings.
This is where a site measure is valuable. It confirms the actual wall dimensions and picks up details that are easy to miss on a drawing. For renovations across Brisbane, the Gold Coast and surrounding areas, Aurex Glass can measure, specify and install a custom mirror to suit the completed space.
Choose an edge finish that suits the room
A polished edge is a clean, versatile choice for most wall mirrors. It suits frameless bathroom designs and lets the tile, joinery and tapware lead the overall look.
A framed mirror can create more definition, especially where the vanity has a bold finish or the room needs a stronger outline. Keep the frame finish aligned with the rest of the room. Matt Black, Chrome, Brushed Gold and Matt Natural can all work well when selected to suit the tapware and hardware already specified.
The practical consideration is edge clearance. A frame adds to the overall mirror size, so check that the quoted dimensions refer to the finished external measurement. This matters when fitting between wall lights, cabinets or tiled returns.
A proportion that feels right lasts longer than a trend
The best bathroom mirror is sized for the vanity, positioned for daily use and measured against the finished wall. Start with even margins, allow for lighting and fittings, then choose a shape that supports the room rather than competing with it. A careful measure before manufacture keeps the final installation clean, considered and made to fit.