How to Use the Cone Volume Calculator

Enter the cone's radius and height. Volume and slant height both come out below.

volume = ⅓ × π × radius² × height
slant height = √(radius² + height²)

A cone holds exactly one-third the volume of a cylinder with the same base and height — not an approximation, an exact ratio provable with calculus (or, historically, first shown geometrically by Eudoxus long before calculus existed). Slant height is a different measurement entirely: it's the distance along the cone's outer surface from the tip to the base edge, not the straight vertical height, and it comes from treating the radius and height as legs of a right triangle.