How Much Concrete Do I Need?
Concrete is sold and delivered in cubic metres (m³). Here's the simple formula and some worked examples so you can estimate your pour — then use the calculator to confirm.
The formula
Length × Width × Depth
To find the volume of concrete you need, multiply the length by the width by the depth of your pour — with all three measurements in metres. The answer is your volume in cubic metres.
If your depth is in millimetres, divide by 1000 first: 100mm = 0.1m, 150mm = 0.15m, 200mm = 0.2m. Then add 5–10% for wastage and uneven ground.
Use our concrete calculator to do the maths for you — it works in metres or millimetres and adds a wastage allowance. Once you know the volume, our concrete mixes guide covers the mix normally used for driveways, foundations and slabs.
Worked examples
Common projects in cubic metres
Driveway — 10m × 5m × 100mm
10 × 5 × 0.1 = 5m³. With a 5% wastage allowance, order about 5.25m³.
Garage base — 6m × 4m × 150mm
6 × 4 × 0.15 = 3.6m³. With 5% wastage, about 3.78m³.
Patio — 5m × 3m × 100mm
5 × 3 × 0.1 = 1.5m³. With 5% wastage, about 1.58m³.
Foundation strip — 8m × 0.6m × 0.3m
8 × 0.6 × 0.3 = 1.44m³. With 10% wastage, about 1.58m³.
Slab — 4m × 3m × 150mm
4 × 3 × 0.15 = 1.8m³. With 5% wastage, about 1.89m³.
Why it matters
Because you only pay for what you pour
Because we supply volumetric concrete mixed on site, you only pay for the concrete you actually use — so an accurate estimate means less waste and a more accurate quote. If you order too little with a drum wagon you pay a part-load charge; with volumetric you simply mix a bit more on the spot.
Ready to pour?
Tell us what you're pouring and where. We'll come out, measure up and send an itemised quote — usually within 48 hours.