Ellipse Calculator

Enter the two semi-axis lengths to calculate ellipse area and a Ramanujan perimeter approximation.

Semi-major axis a

Semi-minor axis b

Area = 87.964594πab

35.153Perimeter approximation

0.820652Eccentricity

Ellipse circumference has no elementary closed form; this uses Ramanujan's highly accurate approximation.

How to use this Ellipse Calculator

Calculate ellipse area, approximate perimeter, and eccentricity. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.