How it works
Each semiaxis is half the corresponding full width. The major semiaxis must be at least as large as the minor one. For a = 5 and b = 3, the focus distance c is 4 and eccentricity e is 0.8. Eccentricity is dimensionless, while c keeps the length unit of the inputs.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Major semiaxis a | 5 | Enter a numeric value. Half the full dimension in that direction. Must be greater than zero. |
| Minor semiaxis b | 3 | Enter a numeric value. Half the full dimension in that direction. Must be greater than zero. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Major semiaxis a
- 5
- Minor semiaxis b
- 3
Complete example results
- Eccentricity e
- 0.8
- Centre-to-focus distance c
- 4
Reading the result
Enter lengths in the same unit. Area uses the square of that unit and volume its cube. Height is perpendicular to the base; use a sloping side only when the input explicitly asks for it.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
What does eccentricity zero mean?
Equal semiaxes give a circle, with both foci at its centre. A nondegenerate ellipse has 0 ≤ e < 1; a zero minor semiaxis is excluded.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method sources: mathworld.wolfram.com