Concrete Mix Ratio Calculator
Calculate the quantities of cement, sand, and aggregate for a given volume of concrete.
Cement (50 kg bags)
6.3 bags
Cement (50 kg bags) vs Concrete Volume Needed
Formula
## Concrete Mix Design by Ratio A mix ratio specifies the proportional volumes of cement : sand : aggregate. ### Method 1. Dry volume = Wet volume x 1.54 (factor accounts for voids and compaction) 2. Divide dry volume by sum of ratio parts 3. Multiply each ratio part by the unit volume 4. Convert cement volume to bags: volume x 1440 kg/m^3 (bulk density) / 50 kg per bag Common ratios: 1:2:4 for M15 (general purpose), 1:1.5:3 for M20 (structural), 1:1:2 for M25 (high strength).
Exemplo Resolvido
1 m^3 of concrete at 1:2:4 ratio.
- 01Dry volume = 1 x 1.54 = 1.54 m^3
- 02Total parts = 1 + 2 + 4 = 7
- 03Cement = 1.54 x 1/7 = 0.220 m^3 = 0.220 x 1440 = 316.8 kg = 6.3 bags
- 04Sand = 1.54 x 2/7 = 0.440 m^3
- 05Aggregate = 1.54 x 4/7 = 0.880 m^3
Perguntas Frequentes
What does the 1.54 dry volume factor mean?
When dry materials are mixed with water and compacted, the volume reduces because water fills air voids. To get 1 m^3 of wet concrete, you need approximately 1.54 m^3 of dry bulk ingredients.
What ratio gives what strength?
1:3:6 gives about M10 (10 MPa). 1:2:4 gives about M15. 1:1.5:3 gives about M20. 1:1:2 gives about M25. These are nominal mixes; designed mixes with specific water/cement ratios give more precise strengths.
How much water do I add?
The water-cement ratio (w/c) typically ranges from 0.40 to 0.60. For M20 concrete, w/c of about 0.50 is common. Too much water weakens concrete; too little makes it unworkable. Add water gradually.
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