Measure your sink in three dimensions before you shop
To find a replacement sink that fits your cabinet opening, you need three measurements: the length and width of the basin itself, and the depth from the rim to the bottom. Most replacement sinks fit standard openings, but your cabinet may have been custom-cut or modified over time. Taking these measurements takes about five minutes and prevents buying a sink that does not fit.
You will also need to know whether your current sink is mounted from above (drop-in) or from below (undermount), because this affects which sinks will work in your space. The mounting style determines how much clearance you need and what the cabinet opening looks like underneath.
Key Takeaways
- Measure the length, width, and depth of your current sink basin with a tape measure, taking the measurement from inside edge to inside edge.
- Check whether your sink is a drop-in (mounted from above the counter) or undermount (mounted below), because replacement options differ for each type.
- Measure the cabinet opening width and depth as well, since the new sink must fit through the hole and sit level on the cabinet rim.
- Note the location of the faucet hole and any existing holes for a sprayer or soap dispenser, because not all replacement sinks have the same hole pattern.
- Bring your measurements and photos to the store or use them when ordering online, so you can compare them against the product dimensions listed in the catalog.
Measure the basin length, width, and depth
Start with the sink basin itself. Place your tape measure inside the sink, at the lowest point of the basin, and measure from the inside edge of one long side to the inside edge of the opposite long side. This is your length. Write it down. Then measure from the inside edge of one short side to the inside edge of the opposite short side. This is your width.
Next, measure the depth. Place the tape measure at the rim (the edge where the sink meets the counter) and measure straight down to the lowest point inside the basin. This tells you how deep the bowl is. If your sink has two basins of different depths, measure both. Most kitchen sinks range from 7 to 10 inches deep, but older sinks are sometimes shallower.
Round your measurements to the nearest half-inch. Sink manufacturers build in small tolerances, so a sink listed as 30 inches long will actually be 29.75 to 30.25 inches. Your measurements do not need to be exact to the eighth of an inch.
Check whether your sink is drop-in or undermount
Look at how your current sink sits in the counter. If the rim of the sink rests on top of the counter surface and you can see the edge of the sink from above, it is a drop-in sink. If the sink is mounted underneath the counter and the counter surface appears to overhang the basin, it is an undermount sink.
This matters because drop-in sinks can often be replaced with other drop-in sinks in the same opening, but undermount sinks require special clips and support brackets underneath. If you want to switch from drop-in to undermount (or vice versa), you may need to modify the cabinet opening or the counter itself, which is a larger job than a straightforward replacement.
Measure the cabinet opening
Open the cabinet doors under your sink and look at the hole cut into the counter. Measure the width of this opening from edge to edge, and measure the depth from the front edge of the counter to the back. These measurements tell you the maximum size sink that will fit through the opening and sit on the cabinet rim.
Your new sink should be at least half an inch smaller than the opening in each direction, so there is room to position it and make sure it sits level. If the opening is 32 inches wide, a 31-inch sink will fit comfortably. If the opening is exactly the size of your current sink, you can usually order the same size again.
Also check whether the cabinet has any obstructions—pipes, braces, or support beams—that might interfere with a deeper or wider sink. Shine a flashlight into the cabinet and look at the underside of the counter. If there is a center support beam, a very deep sink might not fit.
Locate the faucet hole and any additional holes
Look at the counter surface behind your sink. Count how many holes are drilled through the counter: one for the faucet, and possibly one or two more for a sprayer, soap dispenser, or hot-water dispenser. Measure the distance from the faucet hole to the edge of the sink (usually the back edge), and measure the distance from the faucet hole to the left and right edges.
Not all replacement sinks have holes in the same locations. Some sinks come with three holes pre-drilled (faucet, sprayer, soap dispenser), while others have only one. If you want to keep your existing faucet and sprayer, you need a sink with holes that match your current setup. If you are replacing the faucet too, you have more flexibility—you can choose a sink with any hole pattern and have a plumber drill new holes if needed.
Take photos and compare against product specifications
Before you go to the store or start shopping online, take a photo of your current sink from above and from the side. Take a photo of the cabinet opening and the underside of the counter. These images help you remember details and let you show them to a salesperson or compare them against product photos online.
When you find a sink you like, compare your measurements against the product dimensions listed in the catalog or on the website. Manufacturers list length, width, and depth for the basin, and they also list the overall dimensions of the sink unit. Make sure the basin measurements match yours, and make sure the overall dimensions will fit in your cabinet opening. If the product page does not list these measurements, contact the manufacturer or retailer before you buy.
Account for rim width and mounting hardware
The rim is the flat edge of the sink that rests on the cabinet. Measure the width of this rim on all four sides—it is often thicker on the back than on the front. A wider rim gives you more surface to work with when mounting, but it also takes up more space on the counter. If your counter is tight or you have a small opening, a sink with a narrow rim may be your only option.
If you are replacing an undermount sink, check whether the new sink comes with mounting clips and brackets, or whether you need to order them separately. Some manufacturers include them; others charge extra. Ask the retailer what hardware is included before you finalize your order.
Frequently Asked Questions
Do I need to measure if I am replacing my sink with the exact same model?
Not necessarily. If the manufacturer still makes the same model and you know the model number, you can order it directly. However, if the model has been discontinued or updated, the replacement version might have slightly different dimensions or hole patterns. Measuring takes five minutes and prevents surprises.
What if my cabinet opening is not a standard size?
Custom or non-standard openings are common in older homes. Measure the opening carefully and look for a sink that is slightly smaller. If no standard sink fits, you can have a custom sink made or have a fabricator modify your cabinet opening. This costs more but ensures a proper fit.
Can I install a larger sink in the same opening?
Only if the opening is large enough. The new sink must fit through the hole and sit on the cabinet rim with at least half an inch of clearance on all sides. If you want a significantly larger sink, you may need to enlarge the opening, which requires cutting the counter and possibly reinforcing the cabinet.
What if the faucet holes do not match my new sink?
A plumber can drill new holes in the counter or in the sink itself, depending on the material. Drilling through laminate or solid surface counters is straightforward. Drilling through stone or tile requires a specialist. Budget 50 to 150 dollars for this work, depending on your counter material.
Should I measure my old sink or the cabinet opening?
Measure both. The sink basin tells you what size you are used to and what will fit your workflow. The cabinet opening tells you the physical limit of what will fit in your space. Together, these measurements may support your new sink will work.