Bathroom Vanity Size Calculator

Find the right vanity size for a bathroom. Enter the available wall width to get the largest standard vanity that fits and whether a double sink will work.

clear floor (min 21 in.)vanity against wall
Recommended Vanity
in. wide
Largest standard size that fits.

Usage Tip

Measure the narrowest point of the wall — baseboard, trim, and pipes can shrink it. If you are between sizes, the smaller vanity with more clear floor usually feels better than a tight squeeze.

THE MATH
Usable width = Wall width − 2 × side gap
Recommended vanity = largest standard width (18 to 72″) that fits
Double sink generally needs about 60″ or more
Standard vanity widths are 18, 24, 30, 36, 48, 60, and 72″, with depths around 18 to 21″ and heights of 32 to 36″.
A double-sink vanity needs roughly 60″ so the two basins have usable counter between and beside them.
Leave clear floor space in front of the vanity — plumbing codes require at least 21″, and 30″ is more comfortable.
Check the door swing, toilet location, and any side walls; the vanity, its drawers, and the door must all clear them.
Wall-hung and pedestal sinks work where a cabinet will not fit; a vanity also adds storage and counter space.
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.