How to use this calculator
Enter half the longest diameter and half the shortest diameter. The two axes are perpendicular; either semi-axis can be a or b.
Formula
A = πab; q = ((a − b)/(a + b))²; P ≈ π(a + b)(1 + 3q/(10 + √(4 − 3q)))
Worked example
An ellipse with semi-axes 5 m and 3 m has area π × 5 × 3 ≈ 47.1239 m². Its full axis lengths are 10 m and 6 m.
Assumptions and limits
Area uses πab. Perimeter uses Ramanujan’s second approximation, not an exact formula; error increases for extremely elongated ellipses.
Frequently asked questions
Should I enter full width and height?
No. Divide each full axis by two before entering the semi-axes.
What units should I use?
Choose your input unit, then enter every dimension in that unit. The result unit can be changed independently.
Does this include waste or material costs?
No. This is geometric area only. Add openings, overlap, cutting waste, prices and installation requirements separately.
Calculated locally; rounded only for display.