DecorTools
Decor & Furniture

Bathroom Mirror Size Calculator

Determine ideal mirror width, height, and mounting positions for single and double sink bathroom vanities.

Vanity Dimensions

Enter vanity cabinet width and available wall height

Recommended Mirror Size

Sizing and placement measurements

Single Full-Span Mirror

36 × 26.4 in

Leaves balanced margins on either side of vanity

Hanging Height Above Countertop:~5 in above deck
Average Eye-Level Center:~65 in from floor

A mirror width of 36.0 in leaves balanced 2–4 in margins on either side of the vanity. Hang the bottom edge ~5 in above the countertop.

How It Works & Calculation Formula

Formula Summary: Mirror Width = Vanity Width × 0.70 to 0.80 (leaving 2 to 4 inches margin on each side).

Step-by-Step Calculation:

  1. Calculate single mirror width: Vanity Width × 0.75.
  2. Check vertical clearance: Available wall height minus faucet clearance (5 in) and light clearance (4 in).
  3. For double vanities: Allocate one mirror centered over each sink with 3–6 inches gap between them.
  4. Hanging position: Mount bottom of mirror 5–10 inches (12–25 cm) above countertop or 2–3 inches above tall faucets.
  5. Eye level center: Aim for center of glass at ~64–66 inches (162–168 cm) from finished floor.

Worked Example Calculation

Sample Inputs:

  • Vanity Width:48 inches
  • Sinks Count:1
  • Available Height:42 inches

Expected Output:

Recommended mirror: 36.0 in wide × 30.0 in tall. Leaves 6 inches of balanced margin on vanity edges.

Practical Tips & Trade Guidelines

  • Never install a mirror wider than the vanity cabinet beneath it—it makes the vanity look undersized and unbalanced.
  • If using wall sconces on either side of the mirror, choose a mirror width that leaves at least 4–6 inches for each sconce.
  • Medicine cabinets require stud clearance check or surface-mount framing before purchasing.
  • In compact powder rooms, an oversized or round mirror can visually expand the space.

Frequently Asked Questions

Generally no. A mirror should be 2 to 4 inches narrower than the vanity on each side (or 70% to 80% of total vanity width) to maintain proportional visual weight.

Important Renovation Notice

Calculations are mathematical estimates based on standard trade conventions. Always field-verify room measurements, examine packaging labels, and check with a licensed contractor before purchasing materials or starting installation.

Related Calculators

View all tools
Decor & Furniture

Wall Art Size Calculator

Choose the right wall art size and hanging height

Calculate Now
Lighting & Electrical Planning

Recessed Lighting Calculator

Plan recessed can lights grid spacing and lumen targets

Calculate Now
Construction & Finishing

Countertop Calculator

Calculate countertop area, backsplash, and slab yields

Calculate Now