Match the cabinet width to your vanity, keep at least 3 inches of clearance above the faucet and below the lights, and confirm your wall can take a recessed box before you buy.
Get the faucet clearance wrong and every morning starts with a cabinet door clanging into the tap. Get the width wrong and the mirror overhangs the countertop. Whether a recessed cabinet fits depends on what’s behind the drywall — the check most people skip. Sizing takes ten minutes with a tape measure; the wall check takes five more.
What Size Medicine Cabinet Fits Your Vanity?
The cabinet should be the same width as your vanity or narrower — never wider. That’s the rule Kohler’s buying guide states outright, keeping the mirror visually anchored to the counter below. Measure the vanity’s full width, then shop within that number.
Angi’s sizing guide puts standard mirror medicine cabinets at 15–24 inches wide by 20–36 inches high, with double-door models at 30–46 inches wide by the same height range. Height matters less than width, but the bottom edge drives everything: too low fights the faucet, too high leaves bare wall where you want to see your face.
How Much Clearance Above the Faucet and Lights?
Plan for at least 3 inches above the faucet and 3 inches below any light fixture. Kohler names that minimum directly: room to turn the handle, wipe the mirror, and open the door without gouging trim. Measure from the faucet spout top to the cabinet bottom, then cabinet top to light bottom. Under 3 inches on either? Size down.
Side sconces change the math — add their width to your measurement before choosing, since a wide cabinet can crowd the fixtures. Check door swing too; a door arcing into a sconce or trim chips both.
| Install Type | Sizing Priority | Watch For |
|---|---|---|
| Recessed, single vanity | Cabinet ≤ vanity width; 3 in. faucet and light clearance | Wall depth, stud bay width, wiring or plumbing in the cavity |
| Recessed, double vanity | Two 15–24 in. cabinets or one 30–46 in. double | Centering between sconces; matching the rough opening exactly |
| Surface-mount | Cabinet ≤ vanity width; add door-swing depth to projection | Depth projecting into the room; clearing faucets and fixtures |
| With side sconces | Cabinet width plus both fixtures must fit the wall run | Doors hitting sconces; crowded spacing at the edges |
| Lighted or defog model | Same width rules apply, plus power routing | GFCI-protected supply; wiring run before the wall goes back |
Can Your Wall Take a Recessed Cabinet?
A recessed cabinet works only if the cavity has room for the rough opening and nothing important inside. Standard interior walls run about 3.5 inches deep, and a cabinet wider than one stud bay — roughly 14.5 inches between studs — may need a header to carry the load above.
Before cutting, look inside: drain lines, supply pipes, vent stacks, and electrical runs all live in the same cavity, and any one kills the plan. A no-contact voltage tester and stud finder settle most of it in minutes. Lighted, dimmable, and defogging models need power at the cabinet, GFCI-protected per bathroom code. Can’t confirm the cavity is clear? Surface-mount is the honest fallback — it projects into the room, so re-check faucet and door-swing clearance first.
Use the manufacturer’s rough opening formula for that specific cabinet, not a generic measurement — guessing is how cabinets end up an eighth of an inch shy. To compare real models, this roundup of tested bathroom vanity mirror medicine cabinets covers what’s worth buying at each size. Kohler’s full guidance is at Kohler’s mirrors and medicine cabinets buying guide.
What Do People Get Wrong Most Often?
Buying wider than the vanity tops the list — Kohler advises against it, and it’s the hardest to unsee. Skipping faucet and light clearance runs second. The rest cluster around installation: measuring width without counting sconces, ordering recessed before confirming framing and utilities, ignoring rough opening numbers. Each is cheap to avoid with a tape measure and five minutes inside the wall — and expensive to fix after mounting.
FAQs
Should the mirror be the same width as the vanity?
Yes. Kohler recommends a mirror or medicine cabinet the same width as the vanity or narrower, never wider. Matching width anchors the mirror visually to the counter and avoids an unbalanced overhang in a small bathroom.
How much space should be between the faucet and the mirror?
At least 3 inches. Kohler calls for a 3-inch minimum above the faucet and below light fixtures — room to operate the faucet handle, clean the mirror, and open the door without hitting anything.
Do I need an electrician for a lighted medicine cabinet?
Usually yes. Lighted, dimmable, and defogging models need a power supply run to the cabinet, and bathroom circuits are typically GFCI-protected. A licensed electrician can confirm the circuit and pull power before the wall is closed — far cheaper than reopening it later.
References & Sources
- Kohler. “Mirrors and Medicine Cabinets Buying Guide.” Source for the cabinet-to-vanity width rule and the 3-inch faucet and light clearance minimums.
- Angi. “How to Measure for a Mirror.” Source for standard medicine cabinet size ranges, including double-door widths.
- IKEA US. “Mirror Cabinets.” Source for current US category pricing on mirror cabinets.