Fabrication Math

How to Calculate Slab Yield, Cutting Time, and Waste for Stone Countertops

The core math behind fabricating stone and engineered countertops: slab yield, cut time, edge run, and waste, worked with real slab dimensions and feed rates.

Start with slab yield, the ratio of usable finished square feet to gross slab area. A standard quartz slab runs 126 by 63 inches, so gross area is 126 times 63 equals 7,938 square inches, or 55.1 square feet. If a kitchen job nets 38 usable square feet after nesting the parts, yield is 38 divided by 55.1 equals 69 percent. Natural stone with directional veining or fissures typically nets 55 to 65 percent; engineered quartz nesting on the Slab Yield Optimizer commonly hits 70 to 78 percent because the material is uniform and parts rotate freely.

Waste is the inverse side of yield, but you cost it in square feet, not percent. Waste area equals gross slab area minus usable area minus reusable remnant area. For the slab above, if 38 sf is usable and you bank a 6 sf remnant larger than 4 by 2 feet, unrecoverable waste is 55.1 minus 38 minus 6 equals 11.1 square feet. Run this through the Stone Waste Cost calculator at your loaded material rate. At 28 dollars per square foot delivered, that 11.1 sf of scrap represents 311 dollars locked in one slab before any labor.

CNC cutting time depends on cut length and feed rate, not on part count. Total cut path for a typical single-bowl kitchen with a sink cutout, four seams, and a perimeter runs roughly 42 linear feet, or 504 inches. A bridge saw or waterjet cutting 20mm quartz feeds at about 40 to 90 inches per minute depending on hardness. At 60 inches per minute, cut time is 504 divided by 60 equals 8.4 minutes of pure cutting. The CNC Stone Cutting Time tool then adds tool changes, rapid moves, and dwell, typically 35 to 50 percent, giving about 12 to 13 minutes of machine time.

Edge polishing is priced per linear foot of finished edge, so measure the exposed edge run separately from cut path. A U-shaped counter with a 25 foot perimeter but two walls against cabinets might expose only 18 linear feet of polished edge. A CNC edge profiler runs a straight eased edge at 20 to 30 inches per minute and a complex ogee at 8 to 12 inches per minute. For 18 feet, or 216 inches, of ogee at 10 inches per minute, that is 21.6 minutes of spindle time. The Edge Polishing Labor calculator converts spindle minutes plus hand finishing into a labor figure.

Resin fill and sealer are consumable calculations driven by surface area and porosity. Resin fill for natural stone voids uses roughly 1 fluid ounce per 2 square feet of fissured granite, so a 40 sf job needs about 20 ounces; the Resin Fill Cost tool multiplies volume by resin price plus catalyst. Sealer coverage is stated on the label, commonly 150 to 200 square feet per quart for dense quartzite and 70 to 100 for porous marble. For 40 sf of honed marble at 85 sf per quart, you use about 0.47 quarts per coat; two coats is 0.94 quarts. The Sealer Coverage calculator handles multi-coat math.

Lead time is a scheduling calculation, not a labor one, but it drives capacity planning. Template-to-install lead time sums queue time plus process time across templating, programming, cutting, polishing, and install. A shop running 30 jobs a week with a 5 day queue, 1 day of fabrication, and a 2 day install backlog reports a 8 to 10 day template-to-install span. The Template-To-Install Lead Time calculator lets you test how adding a second CNC or a Saturday shift compresses the queue, which is usually the largest single block in the total.

Breakage reserve is a probability-weighted quantity you add to material orders. If historical breakage during handling and install is 3 percent of slabs, and a slab costs 1,540 dollars, expected breakage cost per slab is 0.03 times 1,540 equals 46 dollars. Over 200 slabs a month that is 9,240 dollars you must reserve. The Breakage Reserve calculator converts your break rate and slab value into a per-job accrual so a single cracked slab does not erase a job's margin. Track break rate by material: porcelain and thin quartzite break far more than 20mm quartz.

Published 2026-07-01.