What does the Bathroom Mirror Size Calculator calculate?

Calculate a recommended bathroom mirror width, maximum height, vanity coverage and mounting position from measured clearances.

Can I change the assumptions?

Yes. Enter project-specific measurements, rates, prices, waste allowances and other values using the units shown.

Should I verify the result before ordering or hiring?

Yes. Treat the result as a planning estimate and confirm measurements, product specifications, local requirements and current professional quotes before acting.

Bathroom Mirror Size Calculator

Size a bathroom mirror from the vanity and the available wall area. The calculator keeps the result narrower than the vanity and respects bottom and top clearances.

Vanity Width (in)Available Wall Height Above Counter (in)Side Gap on Each Side (in)Bottom Clearance (in)Top Clearance (in)Countertop Height from Floor (in)

Fill in the required fields to see your result.

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The primary result is recommended mirror width. Supporting results show maximum mirror height, vanity coverage, bottom mounting height and top edge height. Related resources: - [How to Choose a Bathroom Mirror Size](/guides/how-to-use-bathroom-mirror-size-calculator)

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How to Use This Calculator

Enter vanity width, available wall height above the countertop, desired side gap, bottom clearance above the counter or backsplash, and top clearance below the light or ceiling.

Formula & Methodology

Recommended width equals vanity width minus two side gaps. Maximum height equals available wall height minus bottom and top clearances. Vanity coverage expresses mirror width as a percentage of vanity width.

Worked example

A 48 in vanity with 3 in side gaps gives a 42 in mirror. With 42 in of available wall height, 6 in bottom clearance and 4 in top clearance, maximum mirror height is 32 in.

Mirror sizing is partly aesthetic. Sconces, medicine-cabinet depth, faucet height, outlet placement, user height, wall framing and manufacturer mounting requirements can control the final choice.

Planning guide only. Verify wall structure, electrical clearances, mirror weight, hardware and manufacturer installation instructions before mounting.

Related Guides

How to Choose a Bathroom Mirror Size
Learn how to use the Bathroom Mirror Size Calculator, understand the formula and improve the estimate.

Frequently Asked Questions

What does the Bathroom Mirror Size Calculator calculate?: Calculate a recommended bathroom mirror width, maximum height, vanity coverage and mounting position from measured clearances.
Can I change the assumptions?: Yes. Enter project-specific measurements, rates, prices, waste allowances and other values using the units shown.
Why can the final result differ?: Mirror sizing is partly aesthetic. Sconces, medicine-cabinet depth, faucet height, outlet placement, user height, wall framing and manufacturer mounting requirements can control the final choice.
Should I verify the result before ordering or hiring?: Yes. Treat the result as a planning estimate and confirm measurements, product specifications, local requirements and current professional quotes before acting.

Last updated 8/1/2026