Concrete Calculator
Calculate cement bags, sand and aggregate for any concrete grade, with a material cost estimate.
Built & reviewed by Ankit Madia, Founder & Markets Trader
Concrete Material Calculator
This calculator works out how much cement, sand and aggregate you need for a concrete pour, and what those materials will cost. Enter the length, width and thickness of the slab, footing or column, choose the concrete grade, and it returns the number of cement bags plus the sand and aggregate in both cubic feet and cubic meters.
How the Calculation Works
The finished (wet) volume is your length × width × depth. Dry materials take more space than wet concrete, so we scale up:
Dry volume = Wet volume × 1.54
Cement = Dry volume × (cement part / total parts)
Cement bags = Cement volume × 1440 / 50
Sand and aggregate are split from the same dry volume in the grade ratio. Water is estimated at a 0.5 water-cement ratio. For example, M20 has a 1:1.5:3 ratio, giving 5.5 total parts.
Nominal Mix Ratios
| Grade | Mix (C:S:A) | Cement / m³ | Typical Use |
|---|---|---|---|
| M7.5 | 1:4:8 | ~3.4 bags | PCC, levelling |
| M10 | 1:3:6 | ~4.5 bags | PCC under footings |
| M15 | 1:2:4 | ~6.5 bags | Flooring, small foundations |
| M20 | 1:1.5:3 | ~8 bags | RCC slabs, beams, columns |
| M25 | 1:1:2 | ~11 bags | Heavier structural loads |
Practical Notes
- Add 5–10% extra for wastage, spillage and uneven surfaces.
- Sand and aggregate are commonly priced per cft or per brass (1 brass = 100 cft).
- This estimate covers cement, sand and aggregate only — not steel, shuttering, admixtures or labour.
- For RCC structural elements, use a properly designed mix from your engineer rather than a nominal ratio.