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Ellipse Calculator
Enter the two semiaxes of an ellipse to find its area, focal distance, eccentricity and a clearly labeled perimeter approximation.
What can an ellipse calculator find?
Given two positive semiaxes, it identifies the major and minor axes, computes area and focus distance, and estimates the perimeter using Ramanujan’s second approximation.
Frequently asked questions
What can an ellipse calculator find?
Given two positive semiaxes, it identifies the major and minor axes, computes area and focus distance, and estimates the perimeter using Ramanujan’s second approximation.
Are my measurements uploaded?
No. The geometry is calculated in this browser. Your values are not sent to a server or stored by this tool.
How do I calculate the area of an ellipse?
Multiply π by the semi-major axis and the semi-minor axis. If a and b are the semiaxes, area is πab.
Is the ellipse perimeter exact?
No. There is no simple elementary closed form for a general ellipse perimeter. This tool uses Ramanujan’s second approximation and labels it as approximate.
What do the foci and eccentricity mean?
The two foci lie on the major axis at equal distances from the center. Eccentricity ranges from 0 for a circle toward 1 for increasingly elongated ellipses.