Concrete Mix & Volume Estimator
Enter your slab or footing dimensions and concrete grade to get cement bags, sand, and aggregate quantities.
Slabs are typically 100–200mm. Footings vary by design load.
Covers spillage and over-excavation. 5% is a common allowance.
| Quantity | Value |
|---|---|
| Wet (compacted) volume | 15.75 m³ |
| Dry volume (× 1.54 bulking) | 24.255 m³ |
| Cement | 127 bags · 6,350 kg |
| Sand | 6.615 m³ · 10,584 kg |
| Aggregate | 13.23 m³ · 19,184 kg |
| Water (approx., w/c 0.5) | 3,175 liters |
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.