Math
Square pyramid
Find volume, slant height and surface area of a right square pyramid.
Calculators / Math / Ellipse perimeter estimate
Ellipse perimeter estimate calculator
Estimate an ellipse circumference from its two semi-axes.
On this page
Estimated perimeter25.53units
Calculator controls
How to calculate
Estimate an ellipse circumference from its two semi-axes.
Estimated perimeter = pi*(a+b)*(1+3*((a-b)/(a+b))^2/(10+sqrt(4-3*((a-b)/(a+b))^2))) units
Worked example
Semi-major axis: 5; Semi-minor axis: 3.
Estimated perimeter: 25.53 units.
Assumptions and limits
Uses Ramanujan’s second approximation, not an exact elliptic integral. Accuracy varies with eccentricity; use one length unit and enter semi-axes rather than full diameters.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Estimate an ellipse circumference from its two semi-axes.
When this tool is useful
Estimated perimeter = pi*(a+b)*(1+3*((a-b)/(a+b))^2/(10+sqrt(4-3*((a-b)/(a+b))^2))) units
Understanding your inputs
| Input | What to enter |
|---|---|
| Semi-major axis | Enter a number of at least 1e-12 and no more than 1000000000000. |
| Semi-minor axis | Enter a number of at least 1e-12 and no more than 1000000000000. |
Frequently asked questions
What assumptions does this calculation use?
Uses Ramanujan’s second approximation, not an exact elliptic integral. Accuracy varies with eccentricity; use one length unit and enter semi-axes rather than full diameters.
How is the result calculated?
Estimated perimeter = pi*(a+b)*(1+3*((a-b)/(a+b))^2/(10+sqrt(4-3*((a-b)/(a+b))^2))) units