How To Measure A Drop-In Sink

The kitchen sink is the focal point of many kitchens – even if it isn’t an eye-catching, glossy copper sink, it hosts the hub of activity in the kitchen. We wash dishes, rinse produce, fill pots, and clean items using the sink. So, there’s no doubting the quintessential importance of your kitchen sink. 

Perhaps you’re renovating your kitchen, and the old drop-in sink has to go. Maybe you want to buy a new drop-in sink, or you might want to switch it out for a seamless undermount sink. Either way, you’ll need to measure your current drop-in sink. Otherwise, you might buy the wrong size replacement, which can lead to unnecessary issues down the road. 

If that sounds like you, you’re in the right place. Here’s how to measure your drop-in sink. 

What Is A Drop-In Sink?

A drop-in sink, also known as a top-mount sink, differs from the other popular sink styles. Unlike the undermount sinks, which are a popular pick in kitchens, drop-in sinks don’t attach solely to the underside of the countertop. 

Instead of requiring two-part epoxy, clips, or brackets to hold the sink in place (like an undermount sink), drop-in sinks rest on the counter itself. These sinks are characterized by a rim surrounding the bowl of the sink. Once you install the sink, the lip rests on the edge of the countertop. 

Underneath the counter, drop-in sinks are usually secured with additional mounts that hold the sink tight to the countertop. However, not all drop-in sinks require clips to hold them in place, as some are heavy enough that they don’t go anywhere. 

Drop-in sinks are the most popular type of sink for kitchens and bathrooms, as they’re incredibly easy to install, so it’s straightforward enough for beginner DIYers to handle. 

Are Drop-In Sinks Standard Size?

There isn’t necessarily an exact standard sink size, as every scenario varies. Some kitchens and bathrooms are massive and have plenty of space for a sprawling sink, while others are compact and require equally compact sinks. So, because of this, there isn’t necessarily a one-size-fits-all option. 

That said, most standard kitchen sinks measure from 24” to 36” in length. The most common sizes are 30 inches wide and 33 inches wide sinks, but there is some variation.

How To Measure A Drop-In Kitchen Sink

Measuring a kitchen sink isn’t overly difficult (most folks don’t have any issues with this project), but there are a few things you should note going into the process. Since we’re working with a drop-in sink, we have to account for the sink’s rim (the part that rests on the countertop).

If you buy a replacement sink that matches the length without the rim, the new sink might fall through the sink cutout. Or, you could end up with a sink that is too large for the space. So, you’ll need to measure the sink correctly. 

There’s some leeway with sizing when replacing the entire countertop, such as with a complete kitchen renovation. You have more flexibility, as your new countertops usually aren’t cut yet. Even still, measuring the sink before you tear out the old structures doesn’t hurt, so you have a general idea of what size works in the space. 

Here’s how to measure a standard rectangular kitchen sink and prepare for a new one. First, collect your materials:

  • Measuring tape or ruler
  • Blade (for cutting and scraping the caulk)
  • Replacement sink
  • Replacement plumbing (as necessary)
  • Tools to disconnect plumbing and faucet (as needed)

Measure The Sink

Obviously, the first step is to measure the sink itself. If the sink is still installed, you might have a tougher time measuring the depth. However, it’s still doable. You need to measure the length and width of the sink as well as the depth of the sink basin. 

These are all essential measurements, but many folks dismiss depth measurements. It’s an integral part of the whole scheme, especially for folks with limited cabinet space. If you buy a sink that’s too deep, you might not have room for the necessary plumbing underneath. Or, if you purchased a shallow sink, you might’ve short-changed yourself and had room for a deeper sink. 

So, remember to note all three measurements. Using a measuring tape, measure the length across the lip of the sink closest to you when the sink is installed.  Measure from the edge of the sink to the opposite edge. Note the measurement. 

Next, measure the width (the measurement perpendicular to the wall when the sink is installed). Note your measurement. 

Lastly, measure the depth. If the sink is still installed, measure from the underside of the countertop to the bottom of the basin. It’s usually easier to measure the sink when it’s uninstalled, but you can still do it with the sink in place. Remember to measure the depth at the deepest part of the sink – some sinks angle toward the drain to provide better drainage. Note your measurement.  

Measure The Cabinet

Once you measure the sink, it’s time to measure the cabinet. This might not seem relevant to the process, but the new sink needs to fit in the same cabinet (unless you’re replacing everything). 

So, to avoid buying an improperly sized sink, note the measurements of the cabinet. First, measure the depth of the cabinet. Place the measuring tape along the bottom of the cabinet, then measure from the back to the front edge. 

Next, measure the width of the cabinet. Place the tape along the bottom of the cabinet, then measure from the bottom left edge to the right edge (corner to corner). Once you obtain the measurements, subtract one inch from the depth to get your total sink width. Next, subtract approximately four inches from the overall width. 

This will give you the largest sink size the cabinet can handle. Remember, a drop-in sink requires space for the lip to rest on the countertop, so don’t buy an oversized sink. 

Take Out The Old Sink

If you haven’t already, now is an excellent time to remove the old sink. You’ll need to turn off the water to the sink (if applicable), then disconnect and remove the plumbing and faucet. With those parts out of the way, you can cut through the caulk around the rim and loosen the clips underneath the counter. 

Lift the sink out of the cutout, then set it aside. Scrape up the leftover caulk on the countertop, then discard it. Before installing a new sink, clean this area thoroughly so the new caulk secures correctly. 

Measure The Cutout

The last step is to measure the sink cutout in the countertop. Measure the length and width of the hole with your measuring tape, then note the measurements. Pay attention to the holes in the countertop, as some kitchen sinks feature unique placement for the faucet. 

If your countertop has holes drilled in unique places, such as off to the right or left of the center, keep this in mind as you shop for a replacement. 

The cutout will tell you what size sink your countertop has room for. For an undermount sink, your new sink needs to match the cutout size. For drop-in sinks, remember that the sink’s rim rests on the counter, so it needs to be slightly larger than the cutout. The lip will rest on the counter, but the hole should be large enough for the basin to fall through.

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