What is the Orbital Period Calculator?
Calculate orbital period using Kepler's third law with this free orbital period calculator. Enter altitude or orbital radius around Earth, the Moon, Mars, Jupiter, or the Sun, or use custom mass and radius. Get period in minutes, hours, days, and years plus orbital velocity. Runs entirely in your browser with no signup.
How to use the Orbital Period Calculator
- Choose Altitude, Orbital Radius, or Mass + Radius mode.
- Select a central body or enter custom mass and orbital distance.
- Click Calculate to get the orbital period and velocity.
- Review results in seconds, minutes, hours, days, and years.
- Copy the full results and Kepler's law calculation steps.
Common use cases
- Finding ISS orbital period at 408 km altitude
- Calculating geostationary orbit period for a satellite project
- Computing the Moon's orbital period at 384,400 km from Earth
Frequently asked questions
- What is the orbital period formula?
- For a circular orbit, T = 2π√(r³/GM), where T is period, r is orbital radius from the center of the central body, G is the gravitational constant, and M is the central body's mass. This is Kepler's third law.
- What is the ISS orbital period?
- The International Space Station orbits at about 408 km altitude with a period of roughly 92 minutes — about 15.5 orbits per day.
- How long is a geostationary orbit?
- A geostationary satellite at about 35,786 km above Earth's equator has an orbital period of 24 hours, matching Earth's rotation.
- Can I calculate Earth's orbit around the Sun?
- Yes. Use Mass + Radius mode with 1 solar mass and an orbital radius of about 149.6 million km (1 AU) to get roughly 365.25 days.
