Work out frustum volume instantly with clear inputs, formula shown and shareable results.
A conical frustum is a cone with its tip sliced off parallel to the base. Its volume is ⅓πh(R² + Rr + r²), and the curved surface is π(R + r)l with slant height l = √((R − r)² + h²).
Volume
V = ⅓πh(R² + Rr + r²)
Curved area
A = π(R + r)l, l = √((R − r)² + h²)
The formula collapses to πR²h, the cylinder, which is the correct limiting case.
It becomes ⅓πR²h, the full cone. This calculator requires a positive top radius, so use the cone calculator for that case.