OpenTools

Construction & Home Improvement

Countertop Calculator

Estimate countertop area, the number of stone slabs to buy, and an installed cost range for granite, quartz, or marble.

Countertop estimate

Enter each countertop run in inches. The tool finds the finished area, the number of stone slabs, and an installed cost range.

Material
Countertop sections (inches)

Break an L-shape, U-shape, or island into rectangles. Include edge overhang in each measurement.

Slab and edge

Defaults follow the selected material. Override with your supplier's actual slab size.

Enter your own installed $/sq ft to turn the range into a single estimate. Leave blank to use the material range.

How this estimate works

The finished countertop area is area = Σ(length × width) ÷ 144, summed across every rectangular section you enter (break an L-shape or island into rectangles).

Stone is sold in whole slabs, so the count is slabs = ⌈ area × (1 + waste%) ÷ (slab area × yield%) ⌉. The leftover stone is surplus = slabs × slab area − area.

Cost is cost = finished area × $/sq ft (installed) + edge upgrade. The installed $/sq ft figures already include material, fabrication, the standard eased edge, and installation, so cost is driven by the finished area — not by the raw slab area or waste.

For example, a 120″ × 60″ granite run is 50 sq ft. With a 15% waste factor, a 120″ × 70″ slab at 75% yield, that is about 2 slabs and roughly a $2,000–$10,000 installed range before an upgraded edge.

Before you order

Slab dimensions vary, layout waste depends on seam placement and cutouts, and a fabricator ultimately decides how many slabs your specific layout requires. Treat the slab count as a planning guide, then confirm it with your fabricator.

Installed prices vary widely by region, stone tier, edge profile, cutouts, and the fabricator. The cost range is a planning estimate, not a quote; always get a written quote for your material and layout.

Countertop calculator FAQ

Why might a 50 sq ft kitchen need two slabs?
Stone is bought in whole slabs and only part of each slab is usable after L-shapes, cutouts, and seam placement. A 75% yield means a 58 sq ft slab yields about 44 usable sq ft, so a 50 sq ft kitchen typically needs two.
Is the cost estimate a quote?
No. It is a planning range built from US national installed $/sq ft figures for 2026. Regional pricing, stone tier, cutouts, and edge upgrades move the real number. Use it to budget, then get a written quote.
Does this include the sink or cooktop cutout?
No. This first version estimates area, slabs, edges, and a cost range. Cutout labor, seam placement, and demolition or removal are out of scope — confirm those with your fabricator.

Method & sources

Area, slab count, surplus, and cost are computed at full precision and rounded only for display. Slab defaults follow each material; override them with your supplier's actual slab size.

Important limits

  • Covers granite, quartz, and marble only. Laminate, solid surface, butcher block, and other materials are not estimated.
  • Does not price sink or cooktop cutouts, seam placement, removal/demolition, plumbing, or backsplash.
  • Cost is a planning range from US national installed figures, not a quote. Slab count is a guide; the fabricator sets the final count.
  • Does not provide structural, building-code, or design advice.

Reviewed references