Calculate Area of Ellipses, Perimeter, Focus & Eccentricity

An ellipse is like a squished circle. To calculate the properties of an ellipse, two inputs are required, the Major Axis Radius (a) and Minor Axis Radius (b).

The formulas to find the elliptical properties of ellipses including its Focus, Eccentricity and Circumference/Perimeter are shown below:

Area = πab

Focus = √(a2 - b2)

Eccentricity = √(1 - (b/a)2)

Circumference approximation using Ramanujan's formula
= π [ 3(a+b) - √((3a+b)(a+3b)) ]

Major Radius (a)
Minor Radius (b)
Circumference (approx)

*Major Axis and Minor Axis, Perimeter/Circumferences and Focus are in units (e.g. metres), and area will be in unit squares (e.g. metre2). Eccentricity is a ratio.