Concrete Quantity Calculator
Calculate the volume of concrete needed for a slab, patio, or foundation, plus the approximate amounts of cement, sand, gravel, and water to plan for. All the math runs locally in your browser.
How It Works
Before pouring a slab, patio, or foundation, you need to know the required concrete volume to order the right amount, whether as ready-mix concrete delivered by truck or in bags to mix yourself. The tool multiplies length, width, and thickness to get the volume in cubic meters, then applies a standard mix ratio to estimate the amounts of cement, sand, gravel, and water.
Is the 350 kg of cement per m³ mix suitable for all uses?
350 kg/m³ is a common mix ratio for a patio slab or a standard foundation. A structure requiring higher strength (a column, a heavily loaded slab) may need a higher ratio (up to 400 kg/m³), while a less demanding use can get by with a slightly lower one. When in doubt, a professional or the concrete supplier is the best source for adjusting the exact mix.
Should I plan an extra margin on these quantities?
Yes, it's common to allow an extra 5–10% margin to compensate for concrete settling, losses during mixing and transport, and uneven ground that can slightly increase the actual poured volume.
The dimensions you enter stay only on your device: no data is sent to a server for this calculation.