Bathroom Mirror Size Calculator - Vanity Width, Height, and Diameter

A bathroom mirror size calculator is a free planning tool that turns your vanity width, vanity height, and ceiling height into a recommended mirror width, mirror height, and mirror diameter for single, double, round, and oval vanity mirrors. It applies the standard 4 inch width reduction and 12 inch combined clearance so the mirror fits the vanity, leaves room for the faucet, and ends about 6 to 7 inches below the ceiling.

• • Single rectangular vanity mirror: Size a rectangle mirror over a 24 to 48 inch single-sink vanity.
• • Round mirror over a small vanity: Pick a round mirror diameter that fits a powder room vanity.
• • Double vanity with two mirrors: Split a 48 to 72 inch double vanity into two equal mirror panels.
• • Oval mirror with extra height: Size an oval mirror for a tall vanity or a low-ceiling bathroom.

Most sizing mistakes are small but visible. A mirror that matches the vanity width catches the backsplash and crowds the faucet, while a mirror that is too short cuts the head off for tall users. The 4 inch width reduction and 12 inch clearance fix both problems in one measurement.

The same calculator covers round, oval, and double mirrors; toggle the type to switch from a single width to a diameter or per-panel width.

If the new mirror is part of a full vanity refresh, a Tile Calculator turns the same wall and floor dimensions into the backsplash and shower tile counts, so the tile and mirror finish on the same line.

The calculator combines the 4 inch width reduction for a single vanity, the 8 inch total reduction for a double vanity, and the 12 inch combined ceiling and vanity clearance to produce a recommended mirror width, mirror height, and mirror diameter in inches.

• vanityWidth: Outside width of the vanity top in inches.
• vanityHeight: Vanity top height above the floor. Standard comfort-height vanities are 32 to 36 inches.
• ceilingHeight: Bathroom ceiling height. Standard U.S. ceilings are 96 inches (8 ft).
• mirrorType: Shape and configuration: rectangular, oval, round, or double.

The 4 inch width reduction is a 2 inch overhang per side, which looks balanced and keeps the mirror off the faucet handles. The 12 inch clearance splits into 5 to 6 inches above the vanity (for the faucet and backsplash) and 6 to 7 inches below the ceiling (for the light fixture and crown).

For a double vanity the calculator uses an 8 inch total reduction so each panel is 4 inches narrower than its half of the vanity. A low-ceiling warning fires when the resulting mirror height drops below 30 inches.

According to Omni Calculator - Bathroom Mirror Size, a single rectangular vanity mirror should be about 4 inches narrower than the vanity top and the mirror height should equal the ceiling height minus the vanity height minus 12 inches of combined clearance, which gives a 32 by 50 inch mirror for a 36 inch vanity, 34 inch vanity height, and 96 inch ceiling.

According to Bob Vila - The Best Bathroom Mirrors, the width of a vanity mirror should be a few inches less than the width of the sink (the article gives 32 to 34 inches for a 36 inch vanity), the bottom of the mirror should sit 5 to 10 inches above the vanity, and the vanity lighting should be at least 6 inches above the mirror, which matches the 12 inch combined clearance this calculator uses.

If you also need to plan the wall paint around the new mirror, a Paint Calculator turns the same wall width and ceiling height into the primer and finish coverage, so the wall and the mirror are repainted in the same visit.

Four ideas come up again and again when you size a vanity mirror. Understanding them keeps the mirror width, height, and diameter in proportion to the vanity and the room.

Treat the 4 inch reduction and the 12 inch clearance as starting points. Drop the bottom gap to 4 inches in a powder room for a taller mirror, and push the top gap to 8 inches in a tall-ceiling primary bath to leave room for a sconce.

To know the wall area the mirror leaves uncovered, a Wall Square Footage Calculator turns the same wall width and ceiling height into the square footage behind and around the mirror, which is also the area you prime and paint when the mirror comes down.

Four quick steps take you from an empty wall to a mirror order you can place at a home improvement store, mirror shop, or online retailer.

1. 1 Measure the vanity: Measure the outside width of the vanity top in inches and the height of the vanity top above the floor. A 36 inch single vanity is 34 to 36 inches tall in most U.S. homes.
2. 2 Measure the ceiling: Measure the bathroom ceiling height above the floor. Standard U.S. ceilings are 96 inches (8 ft); older homes may be 84 inches (7 ft) and newer homes 108 or 120 inches.
3. 3 Choose the mirror type: Select rectangular, oval, round, or double for a double vanity with two side-by-side panels.
4. 4 Read the result and order: Use the recommended width, height, or diameter to order a stock or custom mirror, then mark the center of the vanity to find the mounting height.

For a 36 inch single vanity at 34 inches tall under an 8 ft ceiling, the calculator returns a 32 by 50 inch rectangular mirror, the standard stock size.

If you want the new mirror to stay clear after a shower, an Air Changes per Hour Calculator sizes the bathroom exhaust fan against the room volume so the steam clears before it fogs the glass.

According to the U.S. Department of Energy - Ventilation guide, a bathroom exhaust fan rated at 50 CFM or more removes moisture and odors after a shower, which is what keeps a large bathroom mirror from fogging in the first place.

The calculator gives you a confident mirror order and a clean mounting plan in under a minute, which is what most homeowners and remodelers need.

• • Get the width right the first time: Stop guessing between a 28, 30, or 32 inch mirror. The 4 inch reduction gives a precise width.
• • Avoid a too-short mirror: A mirror that ends above the vanity top looks amateurish. The 12 inch clearance keeps the bottom 5 to 6 inches above the vanity for the faucet and soap.
• • Cover a tall user or tall ceiling: The ceiling-based height gives a mirror tall enough for most adults, and the low-ceiling warning flags a vanity that needs adjustment.
• • Size round, oval, and double mirrors: Toggle the mirror type to get a diameter for a round mirror, a per-panel width for a double vanity, or a wider rectangle for an oval mirror.
• • Plan the rest of the bathroom refresh: Pair the mirror size with a budget, a tile area, and a paint estimate.

If you are buying a custom-cut mirror, round the recommended dimensions up to the next whole inch so the mirror is slightly larger than the calculator's minimum.

Once you have the mirror width, height, and diameter, a Bathroom Remodel Cost Calculator turns the full plan into a per-line budget so the mirror, vanity, tile, and paint fit inside the same remodel total.

Five things move the recommended mirror width, height, and diameter the most, plus two caveats to keep your expectations realistic.

• • The calculator estimates a comfortable stock-size mirror based on the 4 inch width reduction and the 12 inch combined clearance. It does not account for medicine cabinets, recessed mirror cabinets, or frameless mirrors that mount edge to edge on a tiled wall.
• • Vanity and ceiling measurements are often a quarter to half inch off once baseboard, backsplash, and crown molding are installed, so order the mirror in whole inches and confirm the exact size against the wall before you cut or drill.

Run the calculator with two ceiling heights and mirror types before ordering; the difference between a 7 ft and 8 ft ceiling is usually 4 to 12 inches.

Order a slightly larger mirror only when the wall is flat and square, since a 1/2 inch growth margin prevents visible gaps on out-of-plumb walls.