Square footage calculator with slab math built in.
Measure each straight run of counter once, add the backsplash, and we'll do the rest — the slab math, the standard 10% waste factor, and a heads-up if your runs are long enough to require seams. Use the output to walk into a fabricator's office with the same square footage they're going to template you to.
Measure once, calculate once
Each straight run of counter is one row. A perimeter L-shape is two runs. An island adds a third.
How the math works
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×Each run: length × depth ÷ 144 = square feet
Standard kitchen depth is 25.5 inches. A 10-foot perimeter run is 120 × 25.5 ÷ 144 = 21.25 sq ft of counter surface. We sum every run you enter.
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+Backsplash adds slab material
A 4-inch lip across 16 feet of perimeter is roughly 5 sq ft. A full-height 18-inch backsplash across the same run is 24 sq ft — sometimes a separate slab. We compute it the same way: length × height ÷ 144.
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%10% waste factor — the fabricator math
Fabricators typically work at 75–80% slab utilization once you account for cutting, layout, and grain-matching. The 10% buffer above your raw square footage covers normal cutting waste. Complex layouts (lots of inside corners, vein-matching across a seam) can push the real number to 15%.
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∥Seam detection on runs over 8 feet
Slabs come in roughly 9 × 5 to 10 × 6-foot sheets. A run longer than 96 inches will almost always need a seam. We flag it in the breakdown so you can plan where the seam will land — a design decision that usually gets handed to the fabricator by default.
Three good uses for this number
A measured kitchen is the difference between a precise quote and a sales-pitch quote.
Drop it into the cost calculator
Use this number in the square-footage field of the cost calculator to get an installed-price estimate. Most homeowners are off by 10–20% when they guess the number — the difference shows up as a $1,200–$2,500 swing in the estimate.
Compare fabricator quotes
If three fabricators come back with materially different square footages on the same kitchen, ask why. Either someone is measuring the slab generously (more $) or someone is rounding aggressively (you'll be short).
Estimate slabs needed
Most stone slabs are 100–120 sq ft. Divide your total (with waste) by 80 sq ft to get a usable-yield slab count. Most kitchens land at 1–2 slabs; an island plus full backsplash often needs 3.
A measured kitchen is not a templated kitchen.
If your kitchen has unusual angles, peninsulas, curved islands, or out-of-square corners, a templated site visit by a fabricator will always be more accurate than tape-and-pencil math. This tool is for early-stage estimating — get a digital template before you cut a slab.
Plug this number into the cost calculator →Need help interpreting a fabricator's measurement?
Send the templated drawing and the number you got from this tool. We'll flag any obvious discrepancies before you sign.