Concrete Volume Formula

To estimate concrete volume, use Length × Width × Depth. Always round up by 10% to allow for waste and uneven ground. If you’re unsure, Hunter Concrete Pumps can help you get it right.

Use the Standard Formula

Concrete is measured in cubic metres (m³). To work out how much you need for a slab or footing, use this:

Length (m) × Width (m) × Depth (m) = Volume (m³)

Convert all measurements to metres first. For example:
A slab that’s 8 metres long, 5 metres wide, and 100mm thick (0.1m):

8 × 5 × 0.1 = 4.0m³

But you should never order the exact number. Always round up by 10% to allow for wastage, undulations in the formwork, or spill at the pump.
So in this case, you’d order 4.4m³.

Quick Volume Guide for Common Slab Sizes

Slab Size (m)	Thickness (mm)	Volume (m³)	Add 10% Overrun	Final Order (m³)
4 × 4	100	1.6	0.16	1.8
6 × 6	100	3.6	0.36	4.0
8 × 5	100	4.0	0.40	4.4
10 × 6	150	9.0	0.90	9.9
12 × 10	100	12.0	1.20	13.2

Additional Volume Tips for Special Cases

• Strip Footings: Multiply length by width and depth as usual, but remember footings often vary. Break the job into segments if sizes change.
• Circular Slabs or Pads:
  Use the formula: π × radius² × depth
  Example: A 3m diameter pad at 100mm deep =
  π × (1.5)² × 0.1 ≈ 0.71m³, then add 10% overrun.
• Heavily Reinforced Slabs:
  Dense rebar or mesh can slightly reduce volume needed. We can help adjust for that if required.

Not Sure Of What You Need? Let Us Check It

Send us your slab dimensions, footings plan, or PDF drawings, contact us for an accurate quote.
We’ll run the numbers, round up properly, and even coordinate the mix if you’re using our pump crew.
Hunter Concrete Pump Hire works across Newcastle, The Hunter Valley and much of the Central Coast

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