About this tool
Relate an orbit’s period to its size around a star.
T² = a³ ÷ M with T in years, a (semi-major axis) in astronomical units and M in solar masses.
Formula: T² = a³/M
Example: What do you want to calculate? = Period from distance, Semi-major axis (AU) = 1.524, Star mass (solar masses) = 1 → Orbital period (years) = 1.88138.
Assumes the orbiting body is much lighter than the star.
Quick steps
- Enter your values — every field shows its unit.
- Press Calculate (or Try an example to see how it works).
- Read the results and copy them if you need them elsewhere.
The calculation runs in your browser. Nothing you type is sent to 1CLIK.
FAQ
How does the Kepler’s Third Law Calculator work?
T² = a³ ÷ M with T in years, a (semi-major axis) in astronomical units and M in solar masses.
What should I keep in mind?
Assumes the orbiting body is much lighter than the star.
Is my data sent anywhere?
No. The numbers stay on your device; the page only shows the result.