Stretch a circle and you get an ellipse — the shape of planetary orbits, running tracks, and the obligatory "egg" diagram in every biology textbook. Its area formula is the circle's formula with a clever generalization: instead of one radius squared, you multiply the two different radii, A = πab, where a is the Semi-Major Axis (a) and b is the Semi-Minor Axis (b). The semi-major axis is the longer one, running from center to the farthest edge; the semi-minor is the shorter. For a = 5 and b = 3, the area is 15π, about 47.12. Notice what happens when a equals b: the formula collapses back to πr², confirming the circle is just a well-behaved ellipse. Enter your two axes and read the Area result. The usual mistake is entering full axis lengths (the diameters) instead of the semi-axes — that quadruples your answer, so halve any full-length measurement first.

With the pre-filled defaults — Semi-Major Axis (a) 5, Semi-Minor Axis (b) 3 — the Area Of Ellipse Calculator returns Area 47.1239. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.