Concrete Calculator
Home & ConstructionWork out concrete volume and the cement, sand and aggregate a slab or footing needs.
Runs entirely in your browser — nothing is uploaded
Features
- Volume in cubic metres and cubic feet.
- Nominal mixes from M5 to M25.
- Cement bags, sand and aggregate for the mix chosen.
- Approximate water at a 0.5 water-cement ratio, and the finished weight.
- Runs in your browser.
How to use the Concrete Calculator
- 1Enter the length, width and thickness of the pour.
- 2Choose the mix — M20 is the usual domestic slab.
- 3Read the materials list and order against it.
Frequently asked questions
What is the M20 concrete ratio?
1 part cement to 1.5 parts sand to 3 parts aggregate by volume, giving a characteristic strength of 20 N/mm² at 28 days. It is the standard nominal mix for domestic slabs, columns and beams.
How much does a cubic metre of concrete weigh?
About 2,400 kg — 2.4 tonnes. That is worth knowing before pouring a slab on anything that was not designed for it, and before hiring transport.
Does this include steel reinforcement?
No. Reinforcement is designed for the specific span and load, not estimated from volume, and anything structural should come from an engineer. This gives you the concrete materials only.