Concrete volumes
Circular column or hole volume
- where
- volume of each column or hole (m³)
- diameter (mm)
- depth or height (m)
- total concrete volume (m³)
- number of columns or holes
Explain this equation
Works out the concrete in round columns, piles or post holes.
A circle's area is π d²/4. The diameter is converted from millimetres to metres first. Area times depth gives the volume of one, and multiplying by the number gives the total.
Volume of a cylinder.
Sense check: a 300 mm hole 0.9 m deep holds about 0.064 m³ (64 litres); eight of them about 0.5 m³. Doubling the diameter quadruples the volume.
Watch out: augered holes are often bigger than the auger, and for post holes the post itself takes up some of the volume.
Works out the concrete in round columns, augered holes, tube-formed piers or post holes.
Enter your values to see the result.
Good to know
For augered holes, use the auger diameter plus a little for wander in loose ground. For posts set in the concrete, the post displaces some volume; the post-hole calculator allows for that. Cardboard column tubes are sold by internal diameter, which is the size to enter.
Common mistake
Entering the radius instead of the diameter, which gives a quarter of the true volume.
Limits
Straight-sided cylinders. Belled or under-reamed bases need the bell volume added separately.
Sources
- Geometry: prism volume = plan area × depth; cylinder volume = π d²/4 × h
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow BS 8500, BS EN 206, BS EN 752, Building Regulations Part H, manufacturers’ data and your engineer’s design. Structural concrete and foundations need a competent designer.