Countertop Calculator
A countertop calculator finds the stone area to order. Enter each run's length and depth in inches, subtract shared corners, then add backsplash and waste. Two runs of 120 and 84 inches at 25.5 inches deep with one corner need 31.61 square feet net, or 36.35 with 15 percent waste.
This tool is part of our area calculators. Use it to size a quote request and compare materials. Your fabricator measures and templates the final job.
- Updated October 2026
- Sources Cited
- No Login Required
- Free to Use
Your countertop
Order this much stone
36.35 sq ft
31.61 sq ft net plus 15% waste, or 3.38 sq m
- Counter tops
- 36.13 sq ft
- Corner overlap
- -4.52 sq ft
- Cutouts
- -0 sq ft
- Backsplash
- +0 sq ft
- Waste
- 4.74 sq ft
- Finished edge
- 17 linear ft
Slabs by area
At least 1 slab of 120 x 56.5 in (47.08 sq ft each).
This is an area floor. Your fabricator lays out the pieces, and veining and seams can need more.
Corners counted once
Shared corner squares are subtracted from L and U layouts.
Cutout choice
Keep cutouts in the area or deduct a size you set.
Price comparison
Compare three materials from your own quotes.
Estimates are for planning and quote requests. Fabricators measure, template and lay out the slabs. Prices are never built in. You type them.
How to calculate countertop square footage
Multiply each run's length in inches by its depth in inches. Divide by 144 to get square feet. Add the runs together. Subtract any corner square that two runs share, then add backsplash and waste. A 120 inch run that is 25.5 inches deep is 21.25 square feet.
- Split the counter into straight runs. Measure each at counter height, not at the baseboard.
- Use the real depth. A standard base cabinet with its overhang is 25.5 inches.
- Square feet equal length times depth in inches, divided by 144.
- For an L or U shape, subtract the corner square once for each shared corner.
- Add the backsplash area, decide on cutouts, then add the waste allowance.
For a floor or wall area that is not a counter, use our square footage calculator. For a tile backsplash, use the tile calculator.
Standard countertop depth and overhang
Caesarstone gives 25.5 inches as the most common residential countertop depth. That is a 24 inch base cabinet plus a 1.5 inch front overhang. Islands usually run 27 to 28 inches, and 30 inches or more when seating is added.
| Measure | Typical value | Source |
|---|---|---|
| Base cabinet depth | 24 in | Caesarstone US |
| Front overhang | 1.5 in | Caesarstone US |
| Common residential counter depth | 25.5 in | Caesarstone US |
| Island depth | 27 to 28 in | Caesarstone US |
| Island with seating | 30 in or more | Caesarstone US |
| Breakfast bar or peninsula overhang | about 12 in | Slabwise |
Slabwise says a stone overhang past 12 inches usually needs corbels or hidden steel supports. Ask your fabricator before you plan a deep bar.
Countertop square feet by run length
A single straight run at 25.5 inches deep holds 2.13 square feet for every foot of length. A 10 foot run is 21.25 square feet, or 23.38 with 10 percent waste.
| Run length | Net sq ft | With 10% waste | With 15% waste |
|---|---|---|---|
| 72 in (6 ft) | 12.75 | 14.03 | 14.66 |
| 96 in (8 ft) | 17.00 | 18.70 | 19.55 |
| 120 in (10 ft) | 21.25 | 23.38 | 24.44 |
| 144 in (12 ft) | 25.50 | 28.05 | 29.33 |
| 180 in (15 ft) | 31.88 | 35.06 | 36.66 |
| 240 in (20 ft) | 42.50 | 46.75 | 48.87 |
Add the rows for each run in your kitchen. Subtract a corner square for each L join.
Worked example: an L-shaped kitchen
Run A is 120 by 25.5 inches and run B is 84 by 25.5 inches. They share one corner. The runs add to 36.13 square feet. The corner square takes off 4.52, so the net is 31.61 square feet. Add 15 percent waste for an order of 36.35 square feet.
| Step | Working | Result |
|---|---|---|
| Run A | 120 x 25.5 / 144 | 21.25 sq ft |
| Run B | 84 x 25.5 / 144 | 14.88 sq ft |
| Shared corner | 25.5 x 25.5 / 144 | -4.52 sq ft |
| Net area | 36.13 - 4.52 | 31.61 sq ft |
| Order area | 31.61 x 1.15 | 36.35 sq ft |
Finished edge is the exposed front length, 17.0 linear feet if both runs are edged. The same method gives 26.91 square feet net for a 108 by 25 and 72 by 25 inch pair, which matches the Slabwise example.
How much waste to add to a countertop
Slabwise gives 10 percent for straight runs and 15 percent for L or U shapes. Complex shapes and heavy cutouts run 15 to 20 percent, and book-matched slabs up to 30 percent. These are practitioner figures, not a controlled study. Your fabricator's number wins.
| Layout | Waste to add | Example order, 31.61 sq ft net |
|---|---|---|
| Laminate or butcher block | 5 to 10 percent | 34.77 sq ft at 10% |
| Straight runs | 10 percent | 34.77 sq ft at 10% |
| L or U shapes | 15 percent | 36.35 sq ft at 15% |
| Complex shapes, heavy cutouts or matched veining | 15 to 20 percent | 37.93 sq ft at 20% |
| Mitered waterfall edge | 25 percent or more | 39.51 sq ft at 25% |
| Book-matched slabs | up to 30 percent | 41.09 sq ft at 30% |
The presets in the calculator are 10 percent, 15 percent, 20 percent. You can type any value from 0 to 50.
Backsplash, sink cutouts and edge length
A 4 inch backsplash is usually quoted with the top. A full-height backsplash is measured on its own as height times wall length divided by 144. Most fabricators do not deduct the sink opening because the cutout piece is scrap. Some deduct about 14 by 20 inches.
- Backsplash: enter its length and height. 144 inches of 4 inch backsplash adds 4.00 square feet.
- Cutouts: leave the deduction off unless your fabricator deducts. One 14 by 20 inch cutout is 1.94 square feet.
- Finished edge: leave it blank to use the total run length, or enter only the exposed edge in inches.
- Sinks near seams: tell the fabricator where the sink goes so a seam does not land on it.
A tile backsplash is a different job. Use the tile calculator and the grout calculator.
How many slabs do I need?
Divide the order area by the slab area. Caesarstone lists a 120 by 56.5 inch standard slab of 47.08 square feet. The example order of 36.35 square feet fits one by area. This is a floor. Seams, veining and layout can need more stone.
| Slab | Area, sq ft | Slabs for 36.35 sq ft | Slabs for 70.13 sq ft |
|---|---|---|---|
| Standard 120 x 56.5 in | 47.08 | 1 | 2 |
| Jumbo 124.5 x 61.5 in | 53.17 | 1 | 2 |
| Jumbo 131.5 x 64.5 in | 58.90 | 1 | 2 |
A run longer than the slab needs a seam. The calculator tells you when a run is longer than the slab you picked.
How to compare countertop material costs
Type the quoted price per square foot for up to three materials. The calculator multiplies each by the order area and adds an edge profile price per linear foot if you enter one. It shows the lowest total. Prices are never built in because they change by region, color and shop.
The math is order square feet times price, plus finished edge feet times the edge price. For the example order of 36.35 square feet and 17.0 edge feet, a quote of $1 per square foot gives $36.35 for the stone alone. Scale that by your own quote.
Quotes may add templating, delivery and install. Ask what each quote includes before you compare totals. For a whole-project number, see the construction cost calculator.
What this calculator does not cover
This page sizes rectangular runs. It does not draw a layout, nest pieces on a slab or plan seams. It does not cover curved or angled counters, waterfall legs or sink-specific cutout templates. It shows no prices unless you enter them, and it does not give a labor or install quote.
For a floor around the kitchen, use the flooring calculator. For wall color, use the paint calculator. Inputs are in inches and square feet. Metric input is not built yet.
Methodology and sources
Published October 2026. Last updated October 2026. Next review October 2027.
Reviews: cost calculators · 24 calculators reviewed
Sarah Kim is a Certified Professional Estimator (CPE) with 15 years of construction cost estimation experience. She holds CPE certification from ASPE (member #20-4891). At Turner Construction, she managed material cost analysis on commercial projects ranging from $2M to $45M. At CalcSummit, she writes and verifies all cost estimation and interior finish calculators, updating regional cost benchmarks quarterly using RS Means-informed data.
Full profile →