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Getting concrete quantities right before starting prevents costly mid-project hardware runs. Here is the exact calculation for any slab.
The Formula
Volume = L × W × D | Bags = Volume ÷ 0.035m³ | Always add 10% for waste
Standard formula used by professionals worldwide
Worked Example
Step-by-step
Driveway 4m×3m×0.1m = 1.2m³ → 34 bags + 10% = 38 bags total purchase
Key Concepts
- Accuracy: Results are as accurate as the inputs you provide
- Units: Always use consistent units throughout your calculation
- Verification: Double-check important calculations before making decisions
- Professional advice: For major financial, health, or structural decisions, consult a qualified professional
Privacy and Security
- All calculations run entirely in your browser
- No data is sent to any server
- No sign-up or personal information required
- Your data stays private — always
Frequently Asked Questions
Too much water in concrete?
Reduces strength significantly. Workability improves but compressive strength can drop 50%.
Curing time?
Walkable after 24 hours. Full 28-day strength after 28 days. Avoid heavy loading early.
Mix ratio for driveways?
C25/30 for driveways: approximately 1 cement : 2 sand : 3 aggregate.