Measure Your Sink in Three Dimensions

To order a replacement sink that will fit your cabinet opening, you need three measurements: the length and width of the basin itself, and the depth from the rim to the bottom. These three numbers tell you whether a new sink will sit properly in your existing cabinet cutout and whether it will clear your faucet and plumbing underneath.

Start by clearing out everything under the sink — cleaning supplies, pipes, the works. You need a clear view of the basin and the cabinet opening. Measure with a steel tape measure, not a cloth one, because cloth stretches and gives you false numbers. Write down each measurement in inches, rounded to the nearest quarter inch (so 30.5 inches becomes 30½ inches).

Take photos of your sink from above and from the side before you start measuring. When you are at the store or ordering online, these photos help you remember the exact shape and style you had, and they let a salesperson spot problems you might have missed.

Key Takeaways

  • Measure the length, width, and depth of the basin itself — not the cabinet opening — because sink sizes are standardized but cabinet cutouts vary.
  • A steel tape measure gives you accurate numbers; cloth measures stretch and lead to ordering the wrong size.
  • Measure the depth from the rim down to the lowest point of the basin, because a shallow sink may not fit under your existing faucet.
  • Check the rim type (drop-in, undermount, or farmhouse) because it determines how the sink sits in the cabinet and what cutout size you need.
  • Bring your measurements and photos to the store, or call the manufacturer's customer service line to confirm the new sink will fit your cabinet opening.

Measure Length and Width at the Rim

Place your tape measure across the widest part of the sink, from the outer edge of the rim on one side to the outer edge of the rim on the other side. This is your width. Write it down. Now measure from the front rim to the back rim — that is your length. Both measurements should be taken at the rim, not at the basin bottom, because the rim is what sits on top of the cabinet.

If your sink has rounded corners, measure to the outermost point of the curve. If it is a double basin, measure the entire width of both basins together, not each one separately. You are measuring the footprint of the whole sink as it sits in the cabinet.

Standard kitchen sink widths run 24, 30, 33, or 36 inches. Standard lengths are usually 19, 20, or 22 inches for a single basin, and 30 to 42 inches for a double basin. If your measurements do not match these standard sizes, you may have a custom or older sink — take a photo and bring it to the store so a salesperson can help you find a match.

Measure Depth from Rim to Basin Bottom

Depth is measured from the rim (the top edge where the sink meets the counter) straight down to the lowest point inside the basin. Place your tape measure vertically against the inside wall of the sink and read where it reaches the bottom. This number matters because a shallow sink may not fit under your existing faucet, and a deep sink may not leave enough room for your plumbing to work.

Most kitchen sinks are 7 to 10 inches deep. If your current sink is 8 inches deep and your faucet sits 4 inches above the rim, a new sink that is only 6 inches deep will leave a 6-inch gap between the faucet spout and the basin — water will splash everywhere. Conversely, if you choose a 10-inch-deep sink and your cabinet is shallow, the basin may hit your P-trap or water lines underneath.

If you are replacing a sink in an older home, measure twice. Vintage sinks are sometimes 5 to 6 inches deep, and modern sinks are often 8 to 10 inches. Knowing your current depth helps you decide whether to go deeper (which gives you more room for large pots) or stay the same (which keeps your plumbing and faucet in their current positions).

Identify Your Sink Rim Type

The rim type determines how the sink sits in the cabinet and what size cutout you need. There are three common types: drop-in (the rim rests on top of the counter), undermount (the basin is mounted underneath the counter from below), and farmhouse (the front of the basin is exposed and sits in front of the counter edge).

Look at your current sink. If the rim is visible on top of the counter and you can see the edge of the counter around it, you have a drop-in sink. If the counter appears to overhang the basin and you cannot see the rim from above, you have an undermount sink. If the front of the basin is visible and the counter sits behind it, you have a farmhouse sink.

This matters because an undermount sink needs a different cabinet cutout than a drop-in, and a farmhouse sink needs a special cabinet frame. When you order your replacement, tell the salesperson which type you have now and which type you want. If you are switching types — for example, from drop-in to undermount — you may need to hire a plumber or cabinet maker to modify your cabinet opening.

Measure the Cabinet Opening

Even though you are ordering based on the sink's rim measurements, it is worth measuring the cabinet cutout itself. This tells you whether your cabinet was cut to standard size or whether someone made a custom opening that might not fit a standard replacement sink.

Measure the opening from edge to edge, in both length and width. If the opening is 30 inches wide and you are buying a 30-inch sink, the sink will fit snugly with almost no room to spare. If the opening is 31 inches wide, you have a half-inch of wiggle room on each side, which is normal. If the opening is 28 inches wide and you want a 30-inch sink, the sink will not fit — you would need a 27-inch or smaller model instead.

Write down the cabinet opening measurements separately from the sink measurements. When you talk to a salesperson, give them both numbers. They can tell you whether a standard sink will fit or whether you need to look for a smaller model or have the cabinet opening enlarged.

Check Faucet Hole Spacing and Count

Most kitchen sinks come with pre-drilled holes for the faucet. Count how many holes your current sink has — usually one (for a single-handle faucet), two (for a two-handle faucet), or three (for a two-handle faucet with a sprayer or soap dispenser). Measure the distance between the holes if there is more than one.

When you order a new sink, you can often choose how many holes you want drilled and where they go. If your current faucet has two handles spaced 8 inches apart, and you want to keep that faucet, order a sink with two holes spaced 8 inches apart. If you are buying a new faucet too, you have more flexibility — you can choose a single-handle model and use a sink with just one hole, or add a sprayer hole if you want one.

Some sinks come with holes already drilled; others let you drill them yourself or have a plumber do it. Ask the salesperson what comes with the sink you are ordering. If the holes do not match your faucet, you will need to either fill the old holes (with a plug or epoxy) or drill new ones, which adds cost and complexity.

Confirm Your Measurements Before Ordering

Once you have all three measurements — length, width, and depth — and you know your rim type and cabinet opening size, call the sink manufacturer's customer service line or visit the store with your measurements and photos. A salesperson can look up the exact model you are considering and tell you whether it will fit your cabinet and work with your plumbing.

Many online retailers have a chat feature or phone line where you can describe your sink and get a recommendation without leaving home. Bring up your photos so they can see the style and condition of your current setup. Tell them whether you are keeping your current faucet or buying a new one, because that affects which sink models will work.

If you are ordering online, check the return policy. Some retailers let you return a sink if it does not fit, but others do not. Knowing your measurements correctly the first time saves you the cost and hassle of a return shipment.

Frequently Asked Questions

Do I need to measure if I am just replacing my sink with the exact same model?

No. If you know the brand and model number of your current sink, you can order the same one and it will fit. You can usually find the model number stamped or printed on the underside of the basin. If you cannot find it, take a photo and show it to a salesperson — they can often identify the sink by sight.

What if my cabinet opening is smaller than any standard sink?

You have three options: have a plumber or cabinet maker enlarge the opening, order a custom-made sink from a specialty manufacturer (which costs more), or choose a smaller sink and accept that it will not fill the entire opening. Some people fill the gap with a cutting board or cover panel. Talk to a salesperson about what fits your budget and your kitchen.

Can I put a larger sink in a smaller opening?

No. A sink that is too large will not fit through the opening, and forcing it can crack the counter or damage the cabinet. If you want a larger sink, the cabinet opening must be enlarged first. This usually requires a plumber or cabinet maker and adds several hundred dollars to the project cost.

Does the thickness of the counter matter when I measure?

It matters for undermount sinks, because the mounting hardware needs to fit under the counter. For drop-in sinks, the rim rests on top, so counter thickness does not affect whether the sink fits. If you are switching to an undermount sink, measure your counter thickness and tell the salesperson — they need to know whether your counter is ¾ inch, 1¼ inches, or thicker.

What if I measure wrong and order the wrong size?

Contact the retailer or manufacturer right away. Some will let you return or exchange the sink if it has not been installed. Others charge a restocking fee. A few do not accept returns on sinks at all. Check the return policy before you order, and keep your receipt and all packaging until the sink is installed and working properly.