Countertop Calculator
Add up to three countertop runs and an island in inches, subtract sink or cooktop cutouts, add backsplash and edge length, then estimate slab area to buy and cost.
Interactive calculator · Method COUNTERTOP-AREA-1.0 · Last reviewed: 2026-11-04
Calculate your scenario
Each piece’s area = length × depth in inches ÷ 144.
Your inputs
Default worked example. Edit the inputs to calculate your scenario.
Default worked example
(27.625 sq ft tops + 4.3333 sq ft backsplash) × 1.15 = 36.7521 sq ft × $60.00 + $120.00 edge + $250.00 fee = $2,575.13.
How to use the calculator
Measure each straight run along the wall and its depth to the front edge, add the island if there is one, and the size and number of cutouts. Enter backsplash height and the wall length it runs along, the exposed edge length that gets a finished profile, a waste allowance and the prices you were quoted.
What the result means
A 96 in and a 60 in run at 25.5 in deep total 27.625 sq ft; less one 33 × 22 in sink cutout leaves 22.58 sq ft of top. With 4.33 sq ft of 4 in backsplash and 15% waste you would price about 36.75 sq ft, $2,575.13 at the example prices.
Formula and units
Each piece’s area = length × depth in inches ÷ 144. Net countertop area = runs + island − cutouts (count × cutout length × width ÷ 144). Backsplash = height × length ÷ 144. Slab area to buy = (runs + island + backsplash) × (1 + waste %); cutouts are not subtracted from the purchase because the cut material is usually still paid for. Cost = slab area to buy × price per sq ft + edge feet × edge price + fee.
Worked examples
Two runs, one sink, 4 in backsplash: Run 1 length: 96 in; Run 1 depth: 25.5 in; Run 2 length (0 if none): 60 in; Run 2 depth: 25.5 in; Run 3 length (0 if none): 0 in; Run 3 depth: 25.5 in; Island length (0 if none): 0 in; Island depth: 36 in; Number of cutouts (sink, cooktop): 1 cutouts; Cutout length each: 33 in; Cutout width each: 22 in; Backsplash height (0 for none): 4 in; Backsplash length along the walls: 156 in; Exposed finished edge length: 12 ft; Waste and offcut allowance: 15 %; Material price per sq ft (example): 60 $ per sq ft; Edge profile price per ft (example): 10 $ per ft; Fabrication or install fee (example): 250 $.
Example result: Net countertop area: 22.58 sq ft; Backsplash area: 4.33 sq ft; Slab area to buy (with waste): 36.75 sq ft; Finished edge: 12 ft; Estimated cost: $2,575.13.
One run plus island, two cutouts, no backsplash: Run 1 length: 120 in; Run 1 depth: 25.5 in; Run 2 length (0 if none): 0 in; Run 2 depth: 25.5 in; Run 3 length (0 if none): 0 in; Run 3 depth: 25.5 in; Island length (0 if none): 72 in; Island depth: 36 in; Number of cutouts (sink, cooktop): 2 cutouts; Cutout length each: 30 in; Cutout width each: 21 in; Backsplash height (0 for none): 0 in; Backsplash length along the walls: 156 in; Exposed finished edge length: 20 ft; Waste and offcut allowance: 10 %; Material price per sq ft (example): 75 $ per sq ft; Edge profile price per ft (example): 15 $ per ft; Fabrication or install fee (example): 0 $.
Example result: Net countertop area: 30.5 sq ft; Backsplash area: 0 sq ft; Slab area to buy (with waste): 43.18 sq ft; Finished edge: 20 ft; Estimated cost: $3,538.13.
Limitations and common mistakes
An area estimate only. It does not nest pieces on real slab sizes, place seams, choose overhangs or decide whether cabinets, brackets or corbels will support the top; your fabricator does that from a template. L-shaped corners entered as two runs that overlap are counted twice unless you shorten one run by the other’s depth. Prices and fees are your entries; defaults are examples.
Measuring an L-shaped top as two full runs that both include the corner square, which counts the corner twice.
Sources and assumptions
Method COUNTERTOP-AREA-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.