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MaterialCalc — Countertop Square Foot & Cost Calculator

Estimate prepared 09/01/2026. Estimates only; verify against your plans before ordering.

Countertop Square Foot & Cost Calculator

Add up every straight run along the wall.

Zero if there is no island.

%

Slab yield. Complicated layouts waste more of the slab.

Result

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Countertop is quoted per square foot, but the square footage you need is not the square footage of your kitchen — it is the slab yield, which runs 10 to 20% above the finished area. Edge profile and cutouts are priced separately again. This gives you the area, the edge footage, and what three materials cost across it.

Assumptions used

These are the numbers behind the result. Where one of them is soft, the cost range widens rather than pretending to a precision the data does not have.

Countertop depth
25.5 in

Standard base cabinet depth plus the overhang. An island is deeper.

Home Depot / Lowe's published product data — Published product data, checked 09/01/2026

Prices verified 09/01/2026 (US national average, big-box retail shelf price and regional ready-mix quotes). Regional adjustment: Blended from RSMeans city cost index bands and BLS construction wage differentials.

The formula

Perimeter area = total run × 25.5 in standard depth. Island area = island length × island depth. Add the waste allowance for slab yield. Finished edge = the front of the perimeter runs plus all four sides of the island.

Worked examples

18 ft of counter plus a 6x40 island

Total counter run: 18 Island length: 6 Island depth: 40 Material: quartz Waste: 15

About 55 ft² finished, ordered as 64. Roughly 33 linear feet of edge — the island alone is 15 of it.

Galley kitchen, 22 ft of run, no island

Total counter run: 22 Island length: 0 Island depth: 0 Material: granite Waste: 15

47 ft² finished. Long straight runs have the best slab yield, so 15% waste is generous here.

Small kitchen in laminate, 14 ft

Total counter run: 14 Island length: 0 Island depth: 0 Material: laminate Waste: 15

30 ft². Laminate is a quarter the price of quartz and can be cut on site, which is why it still dominates rental and flip work.

Choosing materials

  • The standard 25.5 in depth is a 24 in base cabinet plus a 1.5 in overhang. Islands are usually deeper, and an island with seating needs 12 to 15 in of overhang, which often needs steel support brackets.
  • Slab yield is real waste. A fabricator cuts your pieces from rectangular slabs, and the offcuts are yours to pay for. Complicated layouts with many short runs waste more.
  • Edge profile is priced per linear foot and the fancy ones are not cheap. On a kitchen with 30 ft of edge, moving from an eased edge to an ogee can add more than upgrading the stone.
  • Cutouts are flat fees — typically $100 to $400 for a sink and similar for a cooktop. Undermount sinks cost more than drop-in because the cut edge is polished.
  • Quartz is engineered and consistent; granite is natural and every slab differs. If you pick granite, go to the yard and tag the actual slab rather than choosing from a sample.

Common questions

How do I measure countertop square footage?

Multiply the total counter run by 25.5 in — 24 in of cabinet plus the overhang — and convert to square feet. Add the island separately at its own length and depth. Then add 10 to 20% for slab yield.

How much does a quartz countertop cost?

Fabricated and installed, typically $55 to $100 per square foot depending on brand and edge profile. A kitchen with 55 ft² of counter lands between $3,000 and $5,500 before cutouts.

Quartz or granite?

Quartz is engineered, non-porous, consistent between slabs and never needs sealing. Granite is natural, every slab is different, and it needs sealing periodically. Prices overlap heavily — the choice is aesthetic more than financial.

Why does the fabricator quote more square feet than I measured?

Because they cut your pieces from rectangular slabs and the offcuts cannot be reused. That yield loss is 10 to 20% on a typical kitchen and more on layouts with many short or angled runs.

What is included in a countertop quote?

Usually the material, fabrication, one edge profile and installation. Sink and cooktop cutouts, upgraded edges, backsplash, and removing the old counters are typically extra. Ask which of those are in the number.

How much overhang for island seating?

Twelve inches minimum for comfortable seating, 15 in is better. Beyond 10 in of unsupported stone you need steel brackets or corbels — the stone will crack under someone leaning on it otherwise.

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