Vanity light size is the quiet reason some bathrooms are flattering and others are not. Most bad bathroom lighting is not a style problem or a bulb problem. It is a sizing and placement problem: the fixture is too small for the mirror, or mounted too high, or sitting in the one spot that creates shadows instead of removing them.
The numbers that fix it are short and easy to remember. Here they are, along with the reason each one exists, because knowing why makes it obvious when to break the rule.
The width rule: 75 to 80 percent of the mirror
A light bar mounted above the mirror should be 75 to 80 percent of the mirror width.
| Mirror width | Light bar width |
|---|---|
| 24 in | 18 to 19 in |
| 30 in | 22 to 24 in |
| 36 in | 27 to 29 in |
| 48 in | 36 to 38 in |
| 60 in | 45 to 48 in |
Go wider than that and the fixture starts to visually overhang the mirror, which reads as a mistake even to people who cannot say why. Go narrower and the outer edges of the mirror sit in shadow, so you end up well lit in the middle of your face and dim at the temples.
There is one exception. If you are deliberately going for the Hollywood dressing room look, with a bar running the full mirror width or wider, you are following a different visual logic and the percentage stops applying. That style works, but it has to look intentional and oversized rather than slightly off.
The rule is tied to the mirror, not the vanity. So settle your mirror size first, then size the light to it.
Mounting height for a fixture above the mirror
Mount the bottom of the fixture 6 to 8 inches above the top of the mirror.
That range keeps the light close enough to reach your face. Push it higher and the fixture stops being a task light and becomes a general ceiling light that happens to be on the wall, which brings back the shadow problem you were trying to solve.
The shade matters here too. A fixture that throws light downward or diffuses it evenly will light a face. One that bounces light up at the ceiling will wash the room and leave you squinting at the mirror.
Flanking sconces: the better option, and the numbers for it
If you have the wall space, a pair of sconces on either side of the mirror beats anything mounted above it. This is not a style preference. It is how the light reaches you.
Light from above casts downward shadows under the brow, the nose and the chin. Light arriving from both sides at roughly eye level cancels those shadows out. It is the same reason photographers and makeup artists set lights at the sides rather than overhead.
Three numbers run this setup.
- Height: 60 to 65 inches from the finished floor to the center of the fixture. Below 60 inches the light starts catching the chin from underneath. Above 65 it begins throwing shadows downward again.
- Spacing: leave roughly 18 to 24 inches of mirror between a sconce and the mirror centerline. On a 36 inch mirror that puts the sconces about 27 to 30 inches apart.
- Pairing: two sconces, one on each side. A single sconce on one side gives you a lit cheek and a shadowed cheek.
Sixty to 65 inches lands at or just above eye level for most adults standing at a vanity. That is the whole point. It is also well above the usual switch height of 48 inches, which is why a sconce installed at switch height looks and performs badly.
Not enough wall for two sconces? A lighted mirror, with the light built into the perimeter, gets you most of the same effect in a narrow bathroom. It is one of the few genuinely useful upgrades for small layouts, along with getting the exhaust fan correctly sized.
Why overhead only lighting is the worst option
A single ceiling fixture or a row of recessed cans above the vanity is the least flattering bathroom light you can install, and it is also the most common.
Light coming straight down fills the eye sockets with shadow, drops a shadow off the nose, and darkens everything under the chin and jaw. It makes people look tired in their own bathroom at eight in the morning, and it makes shaving, makeup and anything requiring a close look genuinely harder.
If recessed cans are all you have and rewiring is off the table, you have two workable fixes. Add sconces at 60 to 65 inches, or swap the mirror for a lighted one. Both put light back at face level, which is the actual problem.
Bulb specs: the two numbers people skip
Fixture choice gets all the attention and bulb spec gets almost none, which is backwards for a room where you look closely at your own face.
Color temperature: 2700K to 3000K. Warmer than 2700K starts reading amber in a mirror and makes it hard to judge color. Cooler than 3000K reads clinical and unflattering. For most residential bathrooms the sweet spot sits at the warm end of that range, around 2700K to 2800K.
Color rendering index: 90 or higher. CRI describes how accurately a light source shows color. A low CRI bulb distorts skin tone and makes clothing and makeup look different in the bathroom than they will outside. This matters more in a bathroom than almost anywhere else in the house, and high CRI bulbs now cost very little extra.
One more practical point: use the same color temperature for every fixture in the room. Mixing a 2700K sconce with a 4000K ceiling can makes the whole room feel slightly wrong in a way that is hard to diagnose.
The three most common sizing mistakes
- Undersizing the fixture. A small sconce on a wide mirror looks unfinished and underlights the space. Scale the fixture to the mirror, not to a generic idea of what a bathroom light should be.
- Mounting too high. Fixtures placed at the ceiling line, or at switch height, both miss. The 60 to 65 inch band for sconces exists because it puts light where the task is.
- Lighting the room instead of the face. Ambient light makes a bathroom pleasant. Task light at face level makes it usable. You want both, and most bathrooms only have the first.
A quick sizing walkthrough
- Settle the mirror size first.
- For a bar above the mirror, multiply the mirror width by 0.75 and 0.8 to get your fixture range.
- Mount the bottom of that bar 6 to 8 inches above the mirror.
- For sconces, center them 60 to 65 inches off the floor with 18 to 24 inches of mirror between each one and the mirror centerline.
- Buy bulbs at 2700K to 3000K with a CRI of 90 or above, and match them across every fixture in the room.
If you are working through a full bathroom plan, the same approach of fixing the big element first and sizing everything to it applies to vanity sizing and to hardware placement.
Frequently asked questions
What size vanity light do I need for a 48 inch mirror?
Roughly 36 to 38 inches wide, which is 75 to 80 percent of the mirror. For a 48 inch vanity with a smaller mirror, size to the mirror rather than the vanity.
How high should a vanity light go above the mirror?
Six to 8 inches from the top of the mirror to the bottom of the fixture. Higher than that and the light stops reaching your face effectively.
How high should bathroom sconces be mounted?
Sixty to 65 inches from the finished floor to the center of the fixture. That puts the light at or just above eye level for most adults, which is where it cancels facial shadows instead of creating them.
Are sconces really better than a light above the mirror?
For lighting a face, yes. Side light at eye level removes the shadows that top light creates. A bar above the mirror is a reasonable second choice and is often the only option when wall space is tight.
What color temperature is best for a bathroom?
2700K to 3000K, with a CRI of 90 or higher. Warmer reads amber in the mirror, cooler reads clinical, and low CRI distorts skin tone and makeup colors.
The whole thing in four numbers
Seventy five to 80 percent of the mirror width. Six to 8 inches above the mirror. Sixty to 65 inches off the floor for sconces. 2700K to 3000K at CRI 90 or better. Get those four right and the fixture you pick can be almost anything, because the light will already be doing its job.