The core rule from retail lighting guides: size the fixture to the mirror, not the countertop, and let the mirror’s edges tell you where to stop.
How Do You Size A Vanity Light To The Mirror?
Measure the mirror’s width, then shop for a light roughly 75% to 80% of that number — never wider than the mirror itself.
The mirror isn’t always the reference.
Final check: if the fixture is wider than the mirror, it reads as oversized from the doorway no matter what the math says.
| Vanity Or Mirror Size | Suggested Light Width | Placement Note |
|---|---|---|
| 24-inch vanity | 20 inches or smaller | Keep within mirror edges |
| 30-inch mirror | 22 to 28 inches | Center over the mirror |
| 36-inch vanity | 20 to 30 inches | About 4 inches under vanity width |
| 42-inch mirror | About 31.5 inches (75% rule) | Never past mirror edges |
| 48-inch vanity | 30 inches or larger | Bar light, centered |
| 60-inch vanity | Sconces per mirror | Light each mirror separately |
| Double vanity | One light per sink zone | Size to each mirror, not the counter |
Where Should A Vanity Light Be Mounted?
Both assume standard 8-foot ceilings and measuring from the finished floor.
Overhead, the goal is soft, even light on the face: too high washes the ceiling, too low throws shadows across your cheekbones. The 75-to-80-inch window keeps the source above eye level without losing it to the ceiling.
Mount sconces on the wall beside the mirror, not above it, with fixture centers just outside the mirror edges — that lights the face from the sides instead of casting a shadow straight down.
Exception: for seated or wheelchair use, overhead lighting often mounts lower so it lands above the user’s eye line; standard height guidance assumes a standing adult.
To compare specific fixtures against these measurements, browsing tested bathroom vanity light fixtures gives you real widths to match against your mirror number.
What Do People Get Wrong?
The most common mistakes are buying a fixture wider than the mirror, mounting it too high or too low, and lighting a double vanity with one centered fixture. Each fails for the same reason: the light gets sized to the room or countertop instead of the surface it must illuminate.
- Oversized fixtures overhanging the mirror edges, making the vanity look cramped.
- Overhead lights hung too low, creating glare at eye level.
- Overhead lights hung too high, mostly lighting the ceiling.
- One centered sconce above the mirror, leaving the face in shadow.
- A single wide bar over a two-sink vanity, under-lighting the outer mirror edges.
The LightsOnline bath light sizing guide supplies the 75% mirror rule for single-mirror setups.
FAQs
Can a vanity light be wider than the vanity?
No. A fixture wider than the vanity or mirror overhangs the edges and reads as oversized. Most guides cap the light at 75% of the mirror width or about 4 inches under the vanity width.
Do I use one light or two over a double vanity?
Two, sized to each mirror or sink zone. One wide centered bar under-lights the outer edges of both mirrors — exactly where faces sit at the sink. Treat each sink as its own lighting zone.
How high should sconces be next to a bathroom mirror?
Centers around 60 to 66 inches from the finished floor, mounted beside the mirror rather than above it, just outside the mirror edges so light reaches the face from both sides.
References & Sources
- The Home Depot. “Vanity Lighting Buying Guide.” Supports the 4-inches-smaller-than-vanity width rule.
- LightsOnline. “The Complete Bath Light Sizing Guide.” Source of the 75% mirror width rule and the 42-inch mirror example.
- Bees Lighting. “How to Choose Vanity Light Size.” Supports the 24- to 36-inch fixture range for single vanities.
