Size right.

Vanities come in six widths and one depth

Bathroom vanities are sold in a short list of widths: 24, 30, 36, 48, 60, and 72 inches cover almost everything on a showroom floor, with 18, 42, and 54 available if you look. Depth is 21 inches on nearly all of them. Height is either 32 inches, the old standard, or 36 inches, marketed as comfort height and matching a kitchen counter. So the entire decision is width, and width is decided by the wall you have and whether you want one sink or two.

The calculator above takes your wall length and clearances and returns the largest vanity that actually fits. This page carries the size chart, the clearance rules that shrink the usable wall more than people expect, the reason 60 inches is the hard floor for a double sink, and what the whole thing costs installed.

The vanity size chart

Two points that decide most of these choices. A 30 inch vanity, the most searched size in the country, gives you roughly eight inches of usable counter once the sink is in, which is why people who buy one often wish they had gone to 36 when the wall allowed it. And going from 60 to 72 inches on a double is not vanity for its own sake: it moves the sinks from 30 inches apart to 36, which is the difference between two people using it at once and two people taking turns.

Clearances: where the wall goes

Code sets two numbers and the NKBA suggests roomier versions of both. From the centerline of the sink to any side wall: 15 inches minimum under IRC R307.1, with 20 recommended. In front of the vanity: 21 inches of clear floor space required, 30 recommended. Neither number is negotiable in an inspection, and the second one is what catches people, because a door swinging into that 21 inch zone fails even if the vanity itself fits the wall.

The practical sequence is to measure the wall, subtract anything that intrudes, then check the door swing before choosing a size. Toilets have their own clearance, 15 inches from the toilet centerline to any obstruction, so a vanity next to a toilet takes that space out of the wall too. In a small bathroom these three rules interact, and the result is usually one size smaller than the tape measure suggested.

Single or double, and the 60 inch question

Two sinks need 30 inches between their centerlines at minimum, with 36 recommended. Each outer sink needs 15 inches to the wall. Add it up and 60 inches is the arithmetic floor for a double vanity, which is exactly why the industry sells its double sink cabinets starting at that width. A 60 inch double works, but the sinks sit at the bare minimum spacing and the counter between them is a strip rather than a surface.

The honest recommendation for a 60 inch wall: consider a single sink with drawers instead. A 60 inch single gives one person a genuinely large counter, real drawer storage, and no plumbing under the middle of the cabinet. Two sinks in that width buy the appearance of a double bath and very little of the function. Above 66 inches the calculus flips and the double is clearly better.

Freestanding, floating, and what goes underneath

A freestanding vanity sits on the floor and hides the plumbing behind a cabinet, which is why it is the default: it forgives rough-in locations that are slightly off. A floating or wall-mount vanity hangs from the wall, shows the floor underneath, makes a small bathroom read larger, and is far less forgiving. It needs solid blocking between the studs, installed before the drywall goes on, and the drain has to exit the wall rather than the floor. Retrofitting one into a bathroom with a floor drain means opening the wall to move the plumbing.

The other under-cabinet issue is the P-trap. Drawer vanities look excellent and then meet the trap, which occupies the exact space the top drawer wants. Manufacturers solve it with U-shaped notched drawers, and it is worth confirming a drawer model has them before buying rather than discovering the top drawer is decorative. Rough-in heights are typically 18 to 20 inches to the drain center and 20 to 22 inches to the supply lines, but the vanity you buy sets the real numbers, so buy the cabinet before the plumber sets the rough-in if you can.

What a vanity costs installed

Counter material moves the number as much as size does. Cultured marble tops with an integrated sink run $100 to $300 and are the reason a complete 30 inch vanity can cost under $400. Quartz runs $300 to $800 on a vanity-sized top, granite slightly less, and both usually arrive as a separate top with an undermount sink, which adds a fabrication step. On a small vanity the material difference is a few hundred dollars, which is the one place in a bathroom where upgrading is genuinely cheap compared to doing the same upgrade in a kitchen.

Where vanity projects go wrong

Measuring the wall, not the usable wall. Door swings, toilet clearance, baseboard, and out-of-square corners all take inches. Measure at counter height as well as at the floor, because old walls are rarely parallel.

Forgetting the top overhangs. A vanity top typically overhangs the cabinet by about an inch on each exposed side, so a 60 inch cabinet needs 61 to 62 inches of clear wall. Buying to the exact wall dimension is how a top ends up needing to be cut.

Assuming the old rough-in will work. Vanity heights changed. Moving from a 32 inch cabinet to a 36 inch comfort height raises everything, and a floating vanity needs the drain in the wall rather than the floor. Confirm before demolition, not after.

Buying a double for a 60 inch wall by reflex. Covered above, and the most common regret in this category. Two sinks at minimum spacing serve two people worse than one sink with a real counter serves either of them.

The rest of the bathroom

A vanity swap rarely travels alone. The countertop calculator prices the top if you are buying it separately, tile behind and around the vanity runs through the backsplash calculator, and the shower in the same room is the shower tile calculator's job. If the plumbing is moving, the drain pipe calculator sizes the lines by fixture units.

Measure the usable wall, subtract for the door, then run the calculator above. It will tell you the largest size that fits and whether two sinks are honestly an option.