Concrete Footing & Pier Volume
Concrete for strip or pad footings and round or square piers (with an optional bell), a waste allowance, and bags from the yield printed on your bag.
Volume per footing and per pier, the total in yd³ or m³ with waste, and a bag count from the yield you enter — with the formulas and the equivalent-shaft note for a bell under a square pier.
Example: A 40 ft × 16 in × 8 in strip footing plus four 12 in sonotubes 4 ft deep comes to 1.78 yd³ before waste, 1.87 yd³ with 5 % — 85 bags at 0.6 ft³ each.
Footings and piers,
as solids.
The shapes assumed, how the bell is treated, and what the bag count depends on.
Shapes
A strip or pad footing is a rectangular prism: length × width × depth. A round pier is a cylinder, π (d/2)² × height; a square pier is side² × height. A bell (belled caisson) under a pier is a cone frustum between the bell diameter at the bottom and the shaft at the top: π h (R² + R r + r²) / 3. Under a square shaft the frustum sits on the circle of equal area, which is stated as an approximation.
Waste and bags
Waste is a percentage you choose, added at the end. Bags come from the yield printed on the bag (cubic feet or litres per bag) — different bag sizes and brands yield different volumes, so none is assumed. The total is also given in m³ for a ready-mix order.
What is not covered
Footing size, pier depth, bearing and reinforcement are design questions; this page only counts the concrete for the dimensions you give. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Solid geometry: rectangular prism, cylinder and cone-frustum volumes (standard mensuration; no empirical factor)
Last reviewed 20 September 2026. How results are checked: How we verify.