Concrete Calculator
Estimate m³ and bags of concrete for any slab.
Amortization schedule
| # | Payment | Principal | Interest | Balance |
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Showing first 12 of months.
Growth over time
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Introduction
Concrete Calculator — Estimate m³ and bags of concrete for any slab. Enter Length (m), Width (m), Thickness (m), Waste (%) to get an instant, accurate result.
Formula
Volume = length × width × thickness, plus a waste percentage allowance; bag count assumes ~2500 kg/m³ density at 40 kg per bag.
Step-by-step
- Enter the Length (m).
- Enter the Width (m).
- Enter the Thickness (m).
- Enter the Waste (%).
- Click Calculate to see your result instantly.
Real-world example
Example: With Length (m) = 5, Width (m) = 4, Thickness (m) = 0.1, Waste (%) = 10, the Concrete Calculator gives Volume M3: 2.2, Volume Without Waste: 2, Bags 40kg: 138.
Frequently Asked Questions
Why add a waste percentage?
To account for spillage, over-excavation, and uneven forms — 10% is a common default allowance.
What if I use different-sized bags?
Scale the bag count proportionally — the volume figure stays accurate regardless of bag size.
What inputs does the Concrete Calculator need?
You'll need to provide: Length (m), Width (m), Thickness (m), Waste (%). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Concrete Calculator?
The Concrete Calculator applies the formula exactly as calculated — Volume = length × width × thickness, plus a waste percentage allowance; bag count assumes ~2500 kg/m³ density at 40 kg per bag. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Concrete Calculator free to use?
Yes, the Concrete Calculator is completely free, requires no signup, and runs instantly in your browser.
About the Concrete Calculator
The Concrete Calculator uses a real, verifiable formula — Volume = length × width × thickness, plus a waste percentage allowance; bag count assumes ~2500 kg/m³ density at 40 kg per bag. — so results are accurate every time, not an approximation.