How to measure for countertops

What you need

• A 25-foot tape measure
• Paper and pencil, or a phone photo you can draw on
• A level, to check the cabinets
• A helper for long runs

Step by step

1. Draw the layout from above: every wall, run, corner, the range, the sink, the dishwasher, and any end that stands open rather than meeting a wall or appliance.
2. Measure each run along the wall, in inches, from wall to end or wall to wall. Measure at the back and again at the front; walls are rarely square, and the longer number is the one that counts.
3. Measure the depth from the wall to the front face of the cabinet doors, then add your overhang, usually 1 to 1½ inches. Standard is about 25 to 25½ inches in total.
4. In an L or U shape, decide which run goes all the way into the corner and which butts into it. Measure the butting run from the face of the first run, not from the wall.
5. Mark the sink center, the cooktop or range opening, and any open end that needs a finished edge.
6. Check each cabinet for level, front to back and side to side. Stone will not bend to an uneven cabinet; shim it first.
7. Note anything that changes height or depth: a raised bar, a deeper island, a window sill that sits low.

Working out square feet

For each rectangle, multiply length by depth in inches and divide by 144. A run 120 inches long and 25½ inches deep is 120 × 25.5 ÷ 144 = 21.25 square feet. Add the runs together, and do not count the corner square twice in an L.

Square feet matter for comparing installed quotes. For prefab pieces, what matters is how many pieces cover your runs.

How many prefab pieces you need

Prefab pieces come in set lengths, so count pieces rather than square feet. The 26-inch piece is 110 inches long and comes with a backsplash. Wider pieces are 108 inches long.

• A run shorter than a piece takes one piece, trimmed to length.
• A longer run takes two or more pieces with a seam between them. Plan seams away from the sink and cooktop, and over a cabinet wall where both sides are supported.
• An L shape usually takes one piece per leg, seamed at the corner.
• An island takes the widest piece that covers its depth plus any seating overhang.
• An offcut from a long piece can sometimes cover a short run, if the width matches.

The 3D countertop planner does this for you: enter your runs, pick a color and width, and it lists the pieces, shows where seams fall and adds up the price.

Before you buy

Measure twice, and have your installer confirm the measurements before any stone is cut. A cut piece can’t be returned. If the counters are being fabricated and installed for you, the installer will template the space to the exact shape anyway; your measurements are for choosing and pricing the stone.