Foundation Calculator
Estimate the concrete volume for a strip foundation and any slab or pad footings in the same run.
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Formula and method
Strip volume is the foundation length times its width and height. Each pad or slab adds length times width times thickness. All volumes are summed and the waste allowance is applied to the total.
How to measure the inputs
- Measure the total centre-line length of the strip foundation.
- Measure the trench width and the depth you will actually pour.
- Add pad footings separately with their own length, width and thickness.
Worked example
Foundation length 19.69 ft; Foundation width 11.81 in; Foundation height 1.64 ft; Waste 8 %; Slab length 6.56 ft; Slab width 3.28 ft; Slab thickness 7.87 in; Slab count 1 → Total concrete volume: 1.836 yd³
Practical tips
- Excavate and pour in sections where possible to keep the trench dry.
- Have the trench inspected before pouring.
- Order concrete slightly early — the trench walls soften if left open.