Math
Ellipse Area Calculator
Use the ellipse area calculator for ovals when you know the two semi-axis lengths.
Try an example
Result
Area
—
- Equal-area circle radius
- —
Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the ellipse area calculator solves
Use the ellipse area calculator for ovals when you know the two semi-axis lengths.
Formula
How to use it
- Enter the two semi-axis lengths.
- Multiply by pi.
- Use square units for the area.
How to read the answer
If a and b are equal, the ellipse area becomes the circle formula pi r^2.
Common mistakes and edge cases
- Use semi-axis lengths, not full width and height.
- Divide full axis lengths by 2 first.
- Keep both axes in the same unit.
Worked examples
Oval area
Area
75.3982
Circle special case
Area
78.5398
Frequently asked questions
What are semi-axes?+
They are half the full width and half the full height of the ellipse.
Can a and b be swapped?+
Yes. Multiplication makes the area the same either way.
How do I use full width and height?+
Divide the full width by 2 for one semi-axis and the full height by 2 for the other before calculating area.
About this calculator
- Written by
- mathcheck editorial team
- Last reviewed
- May 15, 2026
Method
- Uses the values entered by the user and stable formulas documented on the page.
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Last updated: May 15, 2026