Ellipse Area Calculator
Find the area and circumference of an ellipse.
Area of an oval
An ellipse generalizes the circle, and its area is pi times its two semi-axes. Its circumference has no tidy exact formula, so this tool uses a highly accurate approximation.
An ellipse with semi-axes of 5 and 3 has an area of about 47.1 and a circumference near 25.5. When both axes are equal, it reduces to a circle.
Accurate and private
The calculation runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What is the formula?
The area is pi times the two semi-axes multiplied together. Circumference has no simple exact formula, so a close approximation is used.
What are semi-axes?
Half of each of the ellipse’s widths — the distances from the centre to the edge along each axis.
How accurate is the circumference?
It uses Ramanujan’s approximation, which is extremely accurate for typical ellipses.
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