🏗️ Concrete Mix Calculator
Enter a concrete volume and a cement:sand:aggregate ratio to work out the materials for your pour — cement in cubic metres and 50-kg bags, plus sand and aggregate in cubic metres and tonnes.
🏗️ Work Out Your Concrete Materials
What is a Concrete Mix Calculator?
A concrete mix calculator breaks a pour into its ingredients. From the volume of concrete you need and a cement:sand:aggregate ratio, it applies the standard 1.54 dry-volume factor and splits the result into cement (in cubic metres and 50-kg bags), sand, and aggregate (in cubic metres and tonnes).
Enter the volume in cubic metres or cubic yards and set the ratio (1:2:3 is a common default). The tool uses typical bag volume and material densities. These are estimates for planning; for structural work, follow a proper mix design from your engineer or supplier.
❓ Frequently Asked Questions
How do I calculate cement, sand, and aggregate for concrete?
Multiply the wet concrete volume by the 1.54 dry-volume factor, then split the result by the mix ratio. For 1 m³ of concrete at a 1:2:3 ratio, dry volume is 1.54 m³, giving about 0.26 m³ of cement (roughly 7.4 fifty-kilogram bags), 0.51 m³ of sand, and 0.77 m³ of aggregate.
Why multiply by 1.54 for dry volume?
Dry cement, sand, and aggregate contain lots of air and voids. When mixed with water they consolidate, so the loose dry materials take up roughly 1.54 times the final wet concrete volume. The factor accounts for that bulking and for the water filling the gaps, so you buy enough dry material.
What does a 1:2:3 concrete mix mean?
It is the ratio of cement to sand to coarse aggregate by volume: one part cement, two parts sand, three parts aggregate. A 1:2:3 mix is a common general-purpose ratio for footings and slabs. Richer mixes (more cement) give higher strength; leaner mixes use less cement. Set your own ratio in the calculator.
Are these concrete mix quantities exact?
They are estimates for planning. The dry-volume factor, cement bag volume (about 0.0347 m³ per 50-kg bag), and material densities are typical values that vary by source and gradation. For structural or high-strength work, follow a mix design from your engineer or supplier rather than a ratio estimate.