🧱 Concrete Mix Calculator
Calculate cement bags, sand, aggregate, and ready-mix volume for any concrete project.
🏗 Project Type
⚙ Mix Ratio
📖 Common Project Reference
| Project | Typical Mix | Thickness | Notes |
|---|---|---|---|
| Garden path | C20 (1:2:4) | 75–100mm | Light foot traffic |
| Driveway | C30 (1:1:2) | 100–150mm | Car loads, freeze-thaw |
| House slab | C25 (1:1.5:3) | 150mm | Reinforced recommended |
| Strip footing | C25 (1:1.5:3) | 300mm deep | Below frost line |
| Fence post | C20 (1:2:4) | 300mm deep | One bag per post typical |
| Blinding layer | C10 (1:3:6) | 50–75mm | Under slabs, non-structural |
Water-Cement Ratio Guide
The water-cement (w/c) ratio is the weight of water divided by the weight of cement. Lower ratios produce stronger, more durable concrete but are harder to work with.
C10: ~0.70 w/c | C20: ~0.60 | C25: ~0.55 | C30: ~0.45–0.50
For every 50 kg bag of cement you use approximately 25–35 litres of water depending on the mix grade. Never add excess water — it weakens the concrete significantly.