Ellipse Calculator

Calculate ellipse area and circumference from semi-major and semi-minor axes

The longer radius (half of major diameter)

The shorter radius (half of minor diameter)

Results

Enter values and click Calculate to see the result.

Theory & Formula

An ellipse is a closed curve where the sum of distances from any point on the curve to two fixed points (foci) is constant. It has two perpendicular axes: the major axis (longer) and the minor axis (shorter).

Key properties:

  • Area: A = π × a × b
  • Perimeter: No exact formula; use Ramanujan's approximation
  • Eccentricity: e = √(1 - b²/a²), where 0 ≤ e < 1
  • Foci distance: c = a × e from center along major axis
  • When a = b, the ellipse becomes a circle
  • Standard equation: x²/a² + y²/b² = 1
\(A = \pi ab\)

Worked Examples

Example 1

\(a = 5, b = 3 \rightarrow A = 47.12\) sq units

Example 2

\(a = 8, b = 6 \rightarrow A = 150.80\) sq units
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