Concrete Mix & Volume Estimator
Enter your slab or footing dimensions and concrete grade to get cement bags, sand, and aggregate quantities.
How material quantities are derived
A 10m × 10m slab, 150mm thick, M20
With 5% wastage, the wet volume is 10 × 10 × 0.15 × 1.05 ≈ 15.75 m³. Multiplying by the 1.54 bulking factor gives a dry volume of about 24.26 m³. Splitting that across the M20 ratio (1 : 1.5 : 3, five and a half parts total) works out to roughly 127 bags of cement, 10,580 kg of sand, and 19,180 kg of aggregate.
| Material | Quantity |
|---|---|
| Cement | ≈ 127 bags |
| Sand | ≈ 10,580 kg |
| Aggregate | ≈ 19,180 kg |
Choosing a concrete grade
The grade sets the cement-to-aggregate ratio, which sets both strength and cost. Richer mixes (more cement relative to aggregate) cost more per cubic meter but carry more load — matching the grade to the actual job avoids over- or under-specifying.
| Grade | Ratio (C:S:A) | Typical use |
|---|---|---|
| M10 | 1 : 3 : 6 | Plain concrete — leveling course, blinding layer |
| M15 | 1 : 2 : 4 | Light footings, non-structural work |
| M20 | 1 : 1.5 : 3 | RCC slabs, beams — most residential work |
| M25 | 1 : 1 : 2 | Heavier structural elements, higher-load columns |
Common questions
Wet (compacted) volume is how much finished concrete you end up with. But loose dry ingredients — cement powder, sand, and aggregate — contain air gaps between particles that disappear once mixed and compacted. A dry volume factor of 1.54 (a 54% increase) is the standard rule-of-thumb correction used across nominal-mix estimating.