Concrete Slab Cost Calculator (Metric)
Enter your slab dimensions in metres and a price per cubic metre to get the concrete volume you need, plus the delivered material cost with waste built in.
What your result means
The concrete cost is the volume of your slab in cubic metres, bumped up 10% for waste, times your price per cubic metre. Slab volume is the raw size before waste. This figure is the ready-mix material only — forming, reinforcement, pouring, and finishing labour are separate.
How to use this calculator
- Measure the slab length and width in metres.
- Pick a thickness: 10 cm for patios and walkways, 13-15 cm for driveways and garages.
- Get a delivered price per cubic metre from your local ready-mix supplier.
- Read the concrete needed (waste included) and total material cost.
- Budget separately for forms, rebar or mesh, and finishing labour.
The formula
Multiply length by width (in metres) by thickness (centimetres converted to metres) to get cubic metres. Add 10% for spillage and uneven subgrade, then multiply by your price per cubic metre.
Worked example
Say you're pouring a 6 by 6 m patio at 10 cm thick, with ready-mix at $210 a cubic metre. That's 3.6 cubic metres. Add 10% waste and you're ordering about 3.96 cubic metres, so the concrete runs roughly $832. Pouring and finishing labour would add another $1,300 to $2,300 at $35 to $65 a square metre.
Typical slab thickness and ready-mix pricing
| Use | Thickness | Notes |
|---|---|---|
| Walkway / patio | 10 cm | Mesh or fiber mix is usually enough |
| Shed / small pad | 10 cm | Compact the base well |
| Driveway | 13 - 15 cm | Add rebar for heavy vehicles |
| Garage floor | 10 - 15 cm | 15 cm if parking trucks or equipment |
| Ready-mix delivered | — | Commonly $180 - $260 per cubic metre |
Tips & gotchas
- Order 10% extra. Running short mid-pour means a cold joint or a second delivery fee.
- Short-load fees apply under about 1 cubic metre — small pads can cost more per metre.
- A 10 cm slab covers about 10 m² per cubic metre; a 15 cm slab only covers about 6.7 m² per cubic metre.
- Rebar, wire mesh, and a gravel base are extra and matter for crack resistance.
- This is material only. Forming and finishing labour usually doubles the total.
Frequently asked questions
How much does a concrete slab cost?
Material runs about $55 to $75 a square metre for a standard 10 cm slab. With forming, rebar, and finishing labour, installed cost is usually $85 to $160 a square metre.
How many cubic metres do I need for a slab?
Multiply length by width by thickness in metres, then add 10% for waste. A 6 by 6 m, 10 cm slab needs about 3.96 cubic metres with waste.
How thick should a concrete slab be?
10 cm for patios, walkways, and sheds; 13 to 15 cm for driveways and garages that carry vehicles.
Does the price include labour?
No. This calculator covers the ready-mix concrete only. Labour to form, pour, and finish typically adds $20 to $65 per square metre.
Why add 10% waste?
Subgrade is never perfectly level and some concrete is always lost to spillage and over-excavation. Ordering short is far more expensive than a little extra.
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Estimates only — see our full disclaimer.