Concrete quantity toolsConcrete quantities
Belled footing volume
Calculate concrete for a round shaft and the tapered, wider base below it.
Enter your measurements
How it is calculated
V = π × shaft radius² × shaft height above taper + π × taper height / 3 × (shaft radius² + shaft radius × base radius + base radius²).
Keep the full result when using it in another calculation. Results show up to three decimal places; very small positive results use scientific notation (for example, 1e-6). No extra material for waste is added.
Measure the shaft and tapered base separately
Enter the shaft radius, the shaft height above the taper, the bottom radius of the base, and the taper height. These radius fields are not diameters. Measure the shaft height from the top of the tapered base so the two sections do not overlap.
The base is modeled as a circular frustum: a tapered solid with parallel circular ends. Its top radius matches the shaft, and its bottom radius must be at least as large.
Combine the two section volumes
With a 1 ft shaft radius, a 3 ft shaft height, a 2 ft bottom radius, and a 3 ft taper height, the shaft contains about 9.425 ft³ and the frustum contains about 21.991 ft³. Together they contain about 31.416 ft³.
This is only the volume of the supplied geometry. It does not choose a footing size, check soil bearing capacity, or establish whether the foundation is suitable for a structure.
Before you use the result
- The tapered base is a truncated cone, also called a frustum. Its top radius must match the shaft radius, and its bottom radius must be at least as large.
- Measure shaft height from the top of the tapered base. The result is a volume estimate; it does not determine footing dimensions or bearing capacity.