Buying a Bathroom Sink? Here's Exactly What to Measure

The first step to picking the perfect bathroom sink is making sure it fits. Standard bathroom sink widths range from 16 to 24 inches, depths from 12 to 22 inches front-to-back, and basin depths from 5 to 8 inches. To find the right bathroom sink dimensions, grab a tape measure and follow these easy steps.

Step 1: Determine Project Scope

To help you land on the correct bathroom sink dimensions, you'll first have to size up the scope of your project. Whether you're replacing an existing sink or starting from scratch can influence the measurements you will take.

• If you're replacing an existing sink with the same style, simply measure the length, width, and depth of your current sink and choose a replacement with the same measurements.
• If choosing a new style, measure the length and width of your vanity's existing cutout, along with the depth of your old sink. Your replacement should be no longer, wider, or deeper than those measurements.
• If you don't have an old sink to base your measurements off of, we recommend measuring the vanity cutout and using a tape measure to determine the maximum depth a sink could be without obstructing your under sink storage space. This is especially important if you plan to install a drop-in or undermount sink as a large portion of the sink will be beneath the countertop.
• When measuring for a pedestal or wall-mounted sink, your bathroom floor plan and existing plumbing should determine where your sink will go and how big it can be.

Tip!

Review our Guide to Bathroom Sink Styles and Types of Bathroom Sinks to determine the best options for your space.

Step 2: Measure Available Space

When measuring for a drop-in, undermount, or vessel sink, your vanity's available countertop space will determine your sink size.

• To calculate your countertop's usable space, first take stock of its depth, measuring from the front of the vanity to the back wall.
• Next, measure across the top of your vanity's surface to determine the available length. You'll want to leave at least 4 to 6 inches of countertop space on each side of your sink for bath necessities like soap.

Tip!

Take a look at Bathroom Space Planning: Bathroom Layouts to learn how to maximize your space and How to Measure a Kitchen Sink for similar measurement tips.

Step 3: Measure Sink Height

Sink height should be taken from the exterior, measuring from the bottom of your sink to the top rim.

• If purchasing a vessel sink, ensure the height is compatible with your faucet – the spout should reach far enough into the sink so that it's centered with the drain.
• If purchasing an undermount sink or drop-in style, check under your vanity to ensure the sink height clears any structural elements and offers enough clearance for drain assembly.

Tip!

Now that you have the measurements you need for a bathroom sink, learn How to Install a Bathroom Sink.

Frequently Asked Questions

What size sink fits a 30-inch vanity?

A 30-inch vanity typically accommodates a sink that is 16–20 inches wide, allowing for adequate countertop space on each side.

How much countertop space should I leave around a bathroom sink?

Leave 4–6 inches of countertop space on each side of your sink for toiletries and ease of use.

What are standard bathroom sink dimensions?

Standard bathroom sink widths range from 16 to 24 inches, depths from 12 to 22 inches front-to-back, and basin depths from 5 to 8 inches.

How much clearance do I need under the sink for plumbing?

Allow at least 6–8 inches of clearance below the countertop for the drain assembly and P-trap connections.

What's the difference between drop-in and undermount sinks?

A drop-in sink has a visible rim that sits on top of the countertop, while an undermount sink is installed beneath the countertop for a seamless look. Both require measuring the vanity cutout, but undermount sinks need solid-surface countertops for proper installation.

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Ready to find your perfect bathroom sink? (You bet you are.)