Buy the fixture that matches your mirror and your face gets even light. Buy one that’s too wide, too narrow, or hung too high, and you get glare above your brows or shadows across your chin — the two complaints that send people back to the store. Whether you’re sizing a single-sink vanity or a double, the numbers below cover fixture width, mounting height, and sconce placement so you can order once and get it right.
How Wide Should A Vanity Light Be?
Match the fixture to your mirror, not to the vanity — that’s the rule lighting makers and retailers repeat most. Kichler’s planning guide recommends a fixture about 75% of the mirror’s width, and Home Depot’s buying guide puts the range at 75%–80%. The fixture should sit centered and never extend past the mirror edges. If a light overhangs the glass, the extra spill reads as a mistake rather than a design choice.
No mirror to measure? Size the fixture at roughly one-third of the vanity width when you center it over the vanity instead. That formula keeps the light from looking undersized against a wide countertop.
Vaulted or unusually tall ceilings don’t change the width math. Width is a mirror relationship; height is a wall relationship. Don’t let a dramatic ceiling pull the fixture wider than the glass beneath it.
| Vanity Width | Typical Fixture Width | Notes |
|---|---|---|
| 24 inches | 18 inches | Common single-sink size |
| 36 inches | 20–30 inches | Measure the mirror first |
| 48 inches | 30 inches or larger | Stay within mirror edges |
| 60 inches, several mirrors | Wall sconces | One beside each mirror |
| Double vanity, wide mirror | One 36–48 inch bar | Spans both sinks |
| Double vanity, two mirrors | Two matched fixtures | One centered per sink |
| No mirror, centering over vanity | About one-third of vanity width | Fallback formula |
How High Do You Mount A Vanity Light?
That height throws light down onto the face, where you actually need it. Hang it higher and the light aims at the ceiling, leaving your reflection underlit — the most common installation mistake.
The floor number matters most when there’s no mirror to measure against, or when the mirror is floor-to-ceiling. In that case, work from the 72–80 inch range and adjust to your household’s tallest regular user. A fixture that clears everyone’s eyeline by a comfortable margin will read correctly from the doorway.
Side sconces follow a different rule. Flanking the mirror this way lights the face from both sides and softens the shadows a single overhead fixture creates.
Sizing A Double Vanity
A double vanity is two sink zones, not one wide mirror — size it that way. With a single long mirror spanning both sinks, one 36–48 inch fixture can carry the whole span. With two separate mirrors, use two lighter fixtures, one centered over each sink, so each station gets its own even light.
Treating a double vanity like an oversized single is the classic error: one small fixture in the middle leaves both faces dim at the edges. Run the 75% rule against each mirror individually and the two zones balance out.
Ready to compare real options? Our roundup of tested bathroom vanity lights covers fixtures by width and finish so you can match a pick to your measured number.
Before You Buy
Write down your mirror width, then multiply by 0.75 — that’s your target fixture width. Check that the fixture’s listed width fits inside the mirror boundaries with a little room on each side. Confirm your ceiling or wall height allows the 2–3 inch gap above the mirror without crowding a cabinet or soffit.
Wiring is straightforward but unforgiving: connect black to black (hot), white to white (neutral), and the ground wire to the ground post. The exact mounting method depends on your outlet box and mounting plate, so follow the fixture’s own instructions for the bracket and hardware. The sizing guidance here applies to standard residential bathrooms in U.S. homes and covers vanity lights, bath bars, and sconces. Canarm’s sizing guide notes that the final call is yours once the fixture is centered.
FAQs
Does The Fixture Have To Match The Mirror Width Exactly?
No. Aim for about 75% of the mirror width, and treat that as a target rather than a hard rule. A few inches over or under still looks intentional as long as the fixture stays inside the mirror edges. Only overhang and a badly undersized fixture cause real visual problems.
Can One Light Work Over A Double Sink?
Yes, if a single mirror spans both sinks. Choose one long fixture, roughly 36–48 inches wide, centered across the whole span. If your double vanity has two separate mirrors, use two smaller fixtures instead — one centered over each sink — so both faces get even light.
What If My Vanity Has No Mirror Above It?
Size the fixture at about one-third of the vanity width and center it over the vanity. This keeps a bare-wall setup from looking sparse. Once a mirror goes up, remeasure against the glass and adjust if the fixture now extends past the edges.
References & Sources
- Kichler. “Bathroom Lighting Planning and Selecting Tips.” Supports the 75% mirror-width rule and mounting-height guidance.
- Home Depot. “Vanity Lighting Buying Guide.” Supports the 75%–80% sizing range and vanity-width pairings.
- Canarm. “How To Determine Bathroom Vanity Light Sizes.” Supports centering and final-sizing guidance.
