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Cone Surface Area

This calculator helps you find the total surface area of a cone, which includes the area of its circular base and its curved lateral surface. Just enter the radius and the slant height, and we'll do the math for you.

The distance from the center of the base to its edge.

The distance from the apex (tip) of the cone to any point on the circumference of its base.

How it works

This calculator helps you find the total surface area of a cone, which includes the area of its circular base and its curved lateral surface. Just enter the radius and the slant height, and we'll do the math for you.


The Formula
Total Surface Area = πr(r + s) Where:
π (Pi) ≈ 3.14159
r = radius of the base
s = slant height of the cone

Worked Example
  1. Example: Calculating Surface Area

    Imagine a cone with a base radius (r) of 3 cm and a slant height (s) of 5 cm. Using the formula, Total Surface Area = π * 3 * (3 + 5) = π * 3 * 8 = 24π ≈ 75.398 cm². This tool will show you this result clearly.


Tips, Assumptions & Limitations
  • Ensure your radius and slant height are in the same units (e.g., both in cm or both in inches) for a consistent result.
  • If you only have the height (h) and radius (r), you can find the slant height (s) using the Pythagorean theorem: s = √(r² + h²).
FAQ

The surface area of a cone is the total area of its outer surfaces. For a right circular cone, this includes the area of its circular base and the area of its curved side (lateral surface).

If you know the cone's height (h) and radius (r), you can find the slant height (s) using the Pythagorean theorem: s = √(r² + h²). The height, radius, and slant height form a right-angled triangle inside the cone.

The total surface area formula combines two parts: the area of the circular base (πr²) and the lateral (curved) surface area (πrs). Adding these together gives πr² + πrs, which can be factored as πr(r + s).

Companion article

Cone Surface Area Calculator: Master the Formula and Examples

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