Concrete Mix Design Calculator
Calculate exact cement, sand, and aggregate ratios for specific concrete strengths. Features moisture content adjustment for professional mix accuracy.
Advanced: Moisture Correction
About
Professional concrete isn't just about mixing 1 part cement to some sand. To achieve a specific structural strength (measured in PSI or MPa), you need a precise Mix Design. The biggest hidden enemy of strong concrete is the water-to-cement ratio. If your sand pile was rained on last night, it holds significant water. If you add the standard amount of bucket water to wet sand, your mix becomes diluted, weak, and prone to cracking.
This calculator allows you to select a target strength grade and determines the weight of dry materials needed. Crucially, it lets you input the moisture content of your sand and aggregate, automatically reducing the added water and increasing the sand weight to compensate for the wetness. This is how pros get consistent results.
Formulas
1. Nominal Volume Calculation:
Dry volume is roughly 54% more than wet volume due to air voids and shrinkage.
2. Moisture Correction:
3. Adjusted Water Addition:
Reference Data
| Grade | Ratio (C:S:A) | Compressive Strength | Typical Application | W/C Ratio |
|---|---|---|---|---|
| M10 (C7.5) | 1 : 3 : 6 | 10 MPa (1450 PSI) | Patio slabs, pathways | 0.60 |
| M15 (C10) | 1 : 2 : 4 | 15 MPa (2175 PSI) | Pavements, floors | 0.55 |
| M20 (C15) | 1 : 1.5 : 3 | 20 MPa (2900 PSI) | General foundations | 0.50 |
| M25 (C20) | 1 : 1 : 2 | 25 MPa (3625 PSI) | Columns, beams, slabs | 0.45 |
| M30 | Design Mix | 30 MPa (4350 PSI) | Heavy load bearing | 0.42 |