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Measure an Oval Undermount Sink: Cutout, Depth & Drain

How to measure an oval undermount sink?

Measuring an oval undermount sink is all about capturing the right dimensions for the cutout, cabinet clearance, and faucet placement. Because an undermount sink sits beneath the countertop, the measurement you need most often is the opening size (and whether the countertop will be cut for a reveal or an overhang).

Step 1: Confirm what you’re measuring (sink vs. cutout)

If the sink is already installed, you’ll be measuring the countertop opening (the visible oval). If it’s not installed, measure the sink itself and then verify the manufacturer’s cutout template. For undermount setups, the cutout is typically slightly smaller than the sink’s rim to support it from below.

Step 2: Measure the oval opening (length and width)

Use a tape measure and record two numbers:

Length (front-to-back): Measure the longest distance across the oval opening.

Width (left-to-right): Measure the widest distance across the oval opening, perpendicular to the length.

Write both down to the nearest 1/8 inch for best fit with a replacement sink or template.

Step 3: Measure bowl depth and vertical clearance

For a sink that isn’t installed, measure from the top rim down to the deepest point of the bowl. If it is installed, depth is harder to measure accurately, but you can often estimate by measuring from the countertop down to the drain area and subtracting the thickness of the counter if known. Also check cabinet clearance for plumbing and accessories beneath the bowl.

Step 4: Check drain location and faucet spacing

Note whether the drain is centered or slightly offset. For faucet planning, measure from the center of the drain to the backsplash/wall and to any faucet holes (if present). This helps avoid a spout that lands too close to the bowl edge and causes splash.

Step 5: Verify reveal style before ordering

Undermount ovals can be installed with a negative reveal (counter slightly overhangs the sink), a flush reveal, or a positive reveal (counter edge sits inside the rim line). Matching the existing style matters when replacing a sink without re-cutting stone. For more sink planning details and style guidance, see the main guide here: oval sink guide and faucet set article.

FAQ

What’s the difference between sink size and cutout size?

Sink size is the overall dimension of the basin (often measured at the rim), while cutout size is the countertop opening. For undermount sinks, the cutout is usually smaller than the sink’s rim so the counter can support the sink from below.