Isolated Footing Volume Calculator
Enter the top and bottom sizes and height of an isolated (frustum) footing to compute concrete volume and weight for foundation batching.
Input Data
Results
At a glance:An isolated footing expands from a smaller column section to a larger base, shaped like a frustum. Single volume V = h/3 × (top area + bottom area + √(top area × bottom area)). Total volume = single × count; weight = total volume × density ÷ 1000 (tonnes). Stepped footings can be summed in segments; this calculator approximates with a frustum. A larger base spreads column load to the soil and lowers bearing pressure.
Formula
Single V = h/3 × (At + Ab + √(At·Ab))
Total volume = V × count
Weight = total volume × density / 1000
$$V_1 = \frac{h}{3}\left(A_t + A_b + \sqrt{A_t A_b}\right)$$$$V = V_1 n$$$$W = \frac{V\rho}{1000}$$How to Use
- Enter the top and bottom square side lengths (m).
- Enter the footing height and count.
- Confirm the concrete density.
- The tool outputs volume and weight.
Case Studies
Column pad footing
Top 0.4, bottom 1.2, height 0.5, density 2,400.
Single 0.413 m³; weight about 0.99 t.
Multiple column footings
Top 0.5, bottom 1.5, height 0.6, 6 off.
Single 0.78 m³; total 4.68 m³, about 11.2 t.
FAQ
Why is the base larger than the top?
It spreads the column load over a larger base area, lowering soil bearing pressure and avoiding excessive settlement.
How to handle stepped footings?
Sum segments as multiple frustums or rectangular blocks; this calculator approximates the whole as one frustum, usually acceptable error.
Related Tools
References
Content review: Calculatorism Construction Team. Results are for reference only; please refer to the relevant authorities for the official figures.