The Area Of An Ellipse Calculator
An ellipse is a circle that has been stretched along one axis, and its area is the circle area with one radius swapped for the other.
Ellipse area
188.4956
- Ellipse perimeter
- 51.054
- Aspect ratio
- 1.6667
- Equivalent circle radius
- 7.746
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
A = pi x a x b, where a is the semi-major axis and b is the semi-minor axis
- a
- Semi-major axis
- b
- Semi-minor axis
How to check the result by hand
- 1
Identify the two radii
Decide whether the problem gives diameters or radii. If it gives the full width and full length, halve both. The longer one is a and the shorter is b.
- 2
Multiply the two radii
Compute a times b. For a of 10 and b of 6 that is 60.
- 3
Multiply by pi
Take the product times 3.141592653589793. Sixty times pi is about 188.5.
- 4
Sanity-check against the circle
The answer must be smaller than pi times a squared and larger than pi times b squared. If it falls outside that range, the radii are swapped or a diameter slipped in.
For worked examples, common mistakes and the limits of this formula, read the full How To Calculate The Area Of An Ellipse page.