# Countertop Calculator — Slabs, Square Footage & Cost > Free countertop calculator: work out the square footage, granite or quartz slabs to buy and an itemised material, fabrication and edge cost for counters, islands and backsplashes — with waste built in, entirely in your browser. Estimate the square footage, slabs and cost for counters, islands and backsplashes — with waste built in, entirely in your browser. - **HTML page:** https://siteometry.com/en/tools/countertop-calculator - **Category:** [Decorating & Interiors](https://siteometry.com/en/tools/category/decorating-interiors) - **Figures live on the page:** tables, diagrams and worked figures the text refers to ("the table below") are drawn by the page and are not reproduced here. Each section below links to its anchor on the page. - **Runs in the browser:** Siteometry calculators need no account and send no input anywhere — every number below is computed on the visitor's own device. ## Estimate your countertops in eight steps 1. **Choose units** — Pick metric (m, m²) or imperial (ft, ft²); every value converts when you switch. 2. **Pick a material** — Choose granite, quartz, quartzite, marble, laminate, butcher block or concrete — it seeds a typical usable slab size you can edit. 3. **Add your segments** — Add a counter, island or backsplash for each piece — several counter rows model an L- or U-shaped kitchen. 4. **Enter the dimensions** — Type each segment's length and depth (or a backsplash's height); depth chips seed the usual 25.5 in counter, 36 in island and 4 in backsplash. 5. **Choose area or slab** — Set sold-by to slab to count slabs from a usable slab size, or to area for a straight per-square-foot estimate. 6. **Set the waste allowance** — Pick a complexity — simple, L-shape or complex — to set the waste allowance, and override it for a tricky job. 7. **Add prices (optional)** — Enter any of the material, fabrication, edge and cutout prices to build an itemised cost; a material price alone still gives a total. 8. **Read the results, export or print** — Check the area, slabs and cost, then export to CSV or print a clean estimate. _On the page: https://siteometry.com/en/tools/countertop-calculator#howto_ ## Countertop calculator guide The calculator above turns a kitchen's counters, island and backsplash into the numbers a remodel actually needs — square footage, running feet, how many granite or quartz slabs to buy, and an itemised material, fabrication, edge and cutout cost — in metric or imperial, entirely in your browser. This guide explains how slabs are worked out from area and usable slab size, why complex layouts waste more stone, how the optional cost lines add up, and worked examples you can reproduce by hand. _On the page: https://siteometry.com/en/tools/countertop-calculator#countertop-guide-intro_ ## How many slabs of countertop do I need? Stone and engineered countertops are sold by the slab, not the square foot, so the real buying question is how many whole slabs cover your counters once cuts and waste are allowed for. Each slab only yields a usable area smaller than its raw size, because offcuts around sinks, corners and seams cannot all be reused. In short: slabs = countertop area × (1 + waste) ÷ usable slab area, rounded up. The calculator does every step as you type and always rounds up, because you can only buy a whole slab. As a rule of thumb, about 40 ft² of granite counter with a 15% allowance works out to roughly 46 ft², which fits on a single ~55 ft² slab — but add an island or a long run that forces a seam and you can tip into a second slab even though the bare area looks small. _On the page: https://siteometry.com/en/tools/countertop-calculator#how-many-slabs_ ## How this calculator works You describe the job; the calculator handles the arithmetic. Pick a material, add a segment for each counter, island or backsplash and enter its length and depth — always dimensions, never a raw area, so a unit mix-up can't silently double your order. Choose whether you're buying by area or by the slab, and it returns the countertop area, the running feet, the slabs to buy, the realised waste and the leftover. The complexity control sets a sensible waste allowance — more for L- and U-shapes and veined stone, less for a single run — which you can override. Slab size is seeded from the material and stays editable, and the optional price fields let you build an itemised estimate. Switch between metric (m, m²) and imperial (ft, ft²) at any time and every value converts. Results can be exported to CSV for a spreadsheet or printed as a clean estimate. Everything is calculated on your device — nothing you enter is uploaded, and your project is saved only in your own browser. _On the page: https://siteometry.com/en/tools/countertop-calculator#how-calculator-works_ ## Materials and slab sizes Different countertop materials come on different slab sizes, and only part of each slab is usable once you allow for offcuts. The calculator seeds a typical usable slab for the material you pick, which you should replace with the actual size of the slab you're buying — stone slabs in particular vary block to block. The prices below are rough, editable planning figures for a typical 2026 installed job in the United States. They are not quotes: material, region, edge profile, thickness and fabricator all move the number, so always price your own job with a local supplier. _On the page: https://siteometry.com/en/tools/countertop-calculator#materials-and-slabs_ ## Waste: why an L-shape needs more stone Every countertop job loses material to cuts at corners, around sinks and cooktops, and where a long run needs a seam. How much you lose depends mostly on layout: a single straight run wastes little, while L- and U-shaped kitchens and book-matched veined stone cut more and need bigger offcuts. The calculator sets the waste allowance from the complexity you choose, using the typical ranges below, and you can override it for a tricky job. These are general planning figures — the realised waste shown in the results, after rounding up to whole slabs, is usually higher than the allowance you enter. _On the page: https://siteometry.com/en/tools/countertop-calculator#waste-and-complexity_ ## The formulas behind the numbers The results come from a handful of formulas you can check by hand. Area and running feet drive everything; the slab count and cost follow from them. _On the page: https://siteometry.com/en/tools/countertop-calculator#slab-formula_ ## Sample kitchen layouts The same plan-view the tool draws for your kitchen, here on a few common layouts so you can see how counters tile left-to-right, how an island sits detached and where a backsplash strip and sink cutouts land. _On the page: https://siteometry.com/en/tools/countertop-calculator#layouts_ ## Worked examples Each example reproduces what the calculator returns for the given inputs, so you can check the method by hand. Figures round up to whole slabs because you can only buy a whole slab. _On the page: https://siteometry.com/en/tools/countertop-calculator#examples_ ## Common mistakes to avoid Ordering by bare area. Stone is sold by the slab, so 40 ft² of counter is really “how many whole slabs cover 40 ft² plus waste and offcuts” — always round up to slabs, not square feet. Reusing one waste figure everywhere. A single run might lose 10%; an L- or U-shape with cutouts and a seam can lose 20% or more once you round up to whole slabs. Match the complexity to the job. Trusting a stock slab size. Slab dimensions vary block to block and by supplier, so replace the seeded size with the actual usable size of the slab you're buying — it's the number that most affects your slab count. Forgetting edge and cutout costs. On a real quote, the finished edge and sink or cooktop cutouts can add up fast; enter them so the total reflects the whole job, not just the material. Treating the slab count as a cut plan. The estimate assumes an area yield, not a true nesting of pieces onto slabs — a long run needing a seam can require an extra slab the area math won't catch. _On the page: https://siteometry.com/en/tools/countertop-calculator#mistakes_ ## Frequently asked questions Short answers to the questions people most often ask about estimating countertops, slabs and cost with this calculator. ### How many slabs of granite or quartz do I need? Multiply the countertop area by one plus the waste allowance, then divide by the usable slab area and round up. For 40 ft² of counter with a 15% allowance and a 55 ft² usable slab, that's 40 × 1.15 ÷ 55 ≈ 0.84, which rounds up to 1 slab. Add an island or a seamed run and you can tip into a second slab, which is why the calculator rounds up as you type. ### How much waste should I add for countertops? For a single straight run, about 10% is typical. L-shaped kitchens or a run plus an island run around 15%, and U-shapes, heavily veined stone or many cutouts about 20%. The calculator sets a default from the complexity you choose and lets you override it — and shows the realised waste after rounding up to whole slabs, which is usually higher. ### How do I measure my countertops for an estimate? Measure each run's length along the wall and its depth front to back, and enter them as separate segments — one per counter, island and backsplash. For an L or U shape, enter each straight run separately rather than one big rectangle. The calculator sums the areas and running feet and draws a plan-view so you can sanity-check the layout. ### What is the standard countertop depth? A standard base cabinet gives about a 25.5 in (650 mm) finished counter depth, and that's the default the calculator seeds. Islands are often deeper — around 36 in (915 mm) with an overhang for seating. Both are editable, and depth chips let you drop in the usual values with one tap. ### What height should I use for a backsplash? A standard backsplash is about 4 in (100 mm) tall, which the calculator offers as a chip; a full-height backsplash to the upper cabinets is roughly 18 in (450 mm). Enter the run length and the height as a backsplash segment and its area folds into the slabs and cost like any other piece. ### How do I add a kitchen island? Add an island segment and enter its length and depth — islands are commonly around 36 in deep to allow an overhang for seating. Its area folds into the totals and it's drawn detached and centred in the plan-view. Add a cutout if the island has a prep sink. ### How much do countertops cost per square foot? Installed prices vary widely by material and region. As a rough 2026 US guide: laminate about $10–30/ft², butcher block $20–60, granite $40–100, quartz $50–120, and quartzite or marble $60–150. Concrete runs roughly $65–135. These are editable estimates only — price your own job with a local supplier. ### Can I price by the slab instead of per square foot? Yes. Set sold-by to slab and enter a price per slab; the calculator multiplies it by the number of slabs it works out from your usable slab area and waste. This matches how stone yards actually sell — by the slab — rather than a per-square-foot install rate. ### How are sink and cooktop cutouts handled? Cutouts are entered as a count on each counter or island and priced per cutout, since fabricators charge a flat fee for each sink, cooktop or faucet hole. Their area is not subtracted from the material — the offcut is waste, so leaving it in keeps the slab estimate honest. ### How is the finished edge priced? Enter the length of finished, exposed edge and a price per linear foot; the calculator multiplies the two into an edge line. It's a flat per-foot model rather than edge-profile presets, so use the rate your fabricator quotes for the profile you want, such as eased, bullnose or ogee. ### Why doesn't concrete show a slab count? Concrete countertops are cast or poured in place, so there's no purchasable slab to count. Picking concrete forces the calculator into area mode and hides the slab outputs, pricing the job per square foot instead. ### Does it work in metric and imperial? Yes. Enter dimensions in inches and millimetres or feet and metres, and switch the unit toggle at any time — every input, slab size and price converts, so it suits both EU and US countertop jobs. ### Can I export or print the estimate? Yes. Export CSV downloads the per-segment breakdown and cost lines for Excel, Google Sheets or Numbers, and Print / PDF produces a clean estimate with the areas, slabs and itemised cost — handy to take to a fabricator. ### Is the calculator private? Yes. Every calculation runs in your browser — nothing you enter is uploaded to a server. Your project is saved only in your own browser's local storage, so you can close the tab and return to it later. _On the page: https://siteometry.com/en/tools/countertop-calculator#faq_ ## Related calculators - [Carpet Calculator — Broadloom Yardage, Seams, Tiles & Stairs](https://siteometry.com/en/tools/carpet-calculator) - [Paint Coverage & Cost Calculator](https://siteometry.com/en/tools/paint) - [Tile & Flooring Calculator](https://siteometry.com/en/tools/tile) - [Flooring Calculator — Laminate, Vinyl Plank & Hardwood](https://siteometry.com/en/tools/flooring-calculator)