Free Online Calculators
Area + stone size → count, grit & sand quantities
Whether you're laying a simple garden path or a full backyard patio, figuring out how many paving stones you need before you head to the builder's merchant can save you serious time and money. Order too few and you're waiting days for a second delivery. Order too many and you're stuck with leftover stock. A paving calculator takes the uncertainty out of the equation by doing the math for you — fast and accurately.
The process starts with your total area. Say you're paving a 4m × 6m patio using standard 450mm × 450mm slabs laid in a simple row pattern. That's 24 square metres, which works out to roughly 119 slabs — but that's before accounting for waste. Add a standard 10% waste factor for cuts and breakages, and you're looking at around 131 slabs to order. Getting that number right from the start means one trip to the store, not two.
Not all laying patterns are equal when it comes to material usage. A basic row or grid pattern wastes relatively little because cuts are minimal and predictable. Herringbone patterns, popular for driveways and block paving, involve 45-degree angles that increase cut waste — typically 10–15%. Diagonal patterns, where slabs run at 45 degrees to the edges, can push waste even higher, sometimes reaching 20% depending on the shape of your area.
This is exactly why choosing the right waste percentage matters before you buy. Our calculator on simple-calculator.online lets you select your laying pattern and adjust the waste percentage accordingly, so your estimated paver count reflects reality rather than best-case maths.
Beyond the pavers themselves, you'll also need to think about the base layers. A typical patio requires around 100mm of compacted hardcore or gravel, plus a 40–50mm sand or sharp sand bedding layer. For that same 24m² patio, that means approximately 2.4 cubic metres of gravel and 1.1 cubic metres of bedding sand. The calculator handles these quantities automatically, giving you a complete materials list in one go.
Edging stones are often an afterthought, but they're what keeps your whole project from shifting over time. They lock the paved area in place and give it a clean, finished look along borders and pathways. The number of edging stones you need depends on the perimeter of your paved area, not the square footage — so a long, narrow path needs proportionally more edging than a square patio of the same area.
For a 1m × 20m garden path using 250mm edging stones, you'd need roughly 168 edging pieces to line both sides. Getting this figure right alongside your main paver count means a single complete order with nothing missing on installation day.
Divide your total area (length × width in metres) by the area of one paving stone, then multiply by your waste factor. For example, a 3m × 5m area using 600mm × 600mm slabs needs at least 42 slabs, plus 10–20% extra depending on your pattern.
For herringbone patterns, use at least 10–15% waste. For diagonal layouts, go up to 20%. Simple straight row patterns can use as little as 5–10% if your area has clean, straight edges.
Yes. Enter your area and base depth requirements and the calculator will estimate the volume of gravel sub-base and bedding sand you need, giving you a full materials breakdown for the entire project.