Concrete
Concrete Calculator
Enter your measurements to get the volume of concrete to order, and the cement, sand and aggregate for a site mix.
Results update as you type. Nothing to sign up for.
Measurements
Of the slab, footing, path or column.
A domestic path is often 100 mm; a driveway 150 mm or more.
Material
Site mixes show a cement, sand and aggregate breakdown.
You need approximately
1.65m³
of concrete to order
Measured volume
1.5m³
Waste allowance
10%
In litres
1,650L
In cubic yards
2.16yd³
Site-mixed quantities are an estimate for general work. For anything structural — foundations carrying load, reinforced slabs, columns — use a specified mix design from your engineer or supplier.
Volume
- Measured volume
- 1.5 m³1.5 m³
- With 10% waste
- 1.65 m³
- In litres
- 1,650 L
- In cubic feet
- 58.3 ft³
Materials for a 1:2:4 mix
- Dry material needed
- 2.541 m³wet volume × 1.54
- Cement
- 11 bags of 50 kg550 kg
- Sand
- 0.73 m³about 1162 kg
- Aggregate
- 1.45 m³about 2178 kg
- Water
- 275 L0.5 × cement mass
What you measured
- Length
- 5 m
- Width
- 3 m
- Depth
- 10 cm
What to buy
Cement (50 kg bags)
11 bags
Sand
0.73 m³
Aggregate
1.45 m³
Water
about 275 L
Add gradually — workability first, strength suffers if you overdo it.
Want a cost too?
Add your prices in the cost section of the form. We never guess prices — a made-up figure is worse than none.
How to work out how much concrete you need
- Measure the length and width of the pour, and the depth.
- Multiply all three together for the volume. Keep the units consistent — the calculator handles that for you.
- Add a waste allowance, usually 5–10%, because ground is never perfectly level.
- For ready-mix, order that volume. For a site mix, split the dry volume by the mix ratio.
- Work out cement bags from the cement volume, then water from the cement weight.
The concrete formula
Volume = length × width × depth
Order volume = volume × (1 + waste %)
Dry volume = order volume × 1.54
Cement volume = dry volume × cement parts ÷ total parts
Cement bags = cement volume ÷ 0.0347 m³ per 50 kg bag
Water = cement weight × 0.5
Example: a 5 × 3 m slab, 100 mm deep
That is 1.5 m³ of concrete, or 1.65 m³ with a 10% allowance. For a 1:2:4 site mix the dry volume is 2.54 m³, which splits into 0.36 m³ of cement — about 11 bags of 50 kg — with 0.73 m³ of sand, 1.45 m³ of aggregate and roughly 275 litres of water.