Concrete Mix Calculator
Wet Volume and the Volume You Actually Need to Buy Aren't the Same Number
Dry cement, sand, and aggregate take up more space before mixing than the finished wet concrete does, because water and compaction close the gaps between particles. This calculator applies the standard 1.54 dry-volume factor to account for that shrinkage, then splits the resulting dry volume across the mix ratio to get exact material quantities — cement bags, sand volume, aggregate volume, and mixing water.
The Formula
Material Volume = Dry Volume × (Ratio Part / Sum of Ratio Parts)
Cement Weight = Cement Volume × 1,440 kg/m³
Water Required = Cement Weight × Water-Cement Ratio
Worked Example: 1 m³ at a 1:2:4 Mix Ratio
| Quantity | Value |
|---|---|
| Dry volume (wet volume × 1.54) | 1.54 m³ |
| Cement volume | 0.22 m³ |
| Cement weight | 316.8 kg |
| Cement bags (50 kg each) | 6.3 bags |
| Sand volume | 0.44 m³ |
| Aggregate volume | 0.88 m³ |
| Water required | 158.4 liters |
The 1:2:4 ratio is a widely referenced nominal mix historically associated with roughly 15 MPa concrete strength (commonly labeled M15 in nominal-mix design tables), though actual strength depends on cement quality, aggregate grading, and curing — a structural mix design should follow the applicable concrete standard rather than nominal ratios alone.
Where This Gets Used
- Ordering materials for a pour — converting a target concrete volume directly into cement bags, sand, and aggregate quantities to purchase.
- Comparing mix ratios — seeing how a richer ratio (more cement relative to sand and aggregate) changes bag count and cost for the same finished volume.
- Estimating mixing water — getting the water quantity that matches a target water-cement ratio, which directly affects both workability and cured strength.
How to Use This Calculator
- Choose Unit system — Metric (m³) or Imperial (cu yd).
- Enter Concrete Volume Needed.
- Enter Mix Ratio — Cement, Sand, and Aggregate parts (e.g. 1, 2, 4).
- Enter Water-Cement Ratio (defaults to 0.5 if left blank).
- Select Calculate to see cement bags, sand volume, aggregate volume, and water required.
Related Calculations
Check the allowable bearing pressure under a footing with the Soil Bearing Capacity Calculator, or size the beam this concrete will support with the Beam Deflection Calculator.