🛸Orbital Period Calculator
Calculate the orbital period of any satellite or planet using Kepler's Third Law. Works for solar system objects and Earth satellites.
Calculate orbital period using Kepler's Third Law. Supports solar system, Earth satellites, Mars and Jupiter orbiters. Free online.
How to Use Orbital Period Calculator — Step by Step
- 1Select the central body (Sun, Earth, Moon, Mars, or Jupiter)
- 2Enter the semi-major axis of the orbit
- 3Choose the unit (AU, km, meters, or Earth radii)
- 4Click 'Calculate Orbital Period'
- 5View the period in seconds, hours, days, and years, plus orbital velocity
Why Use ToolNest for Orbital Period Calculator?
- 🛸Kepler's Third Law: T² = (4π²/GM)·a³ — exact for circular orbits
- 🌍Supports 5 central bodies: Sun, Earth, Moon, Mars, Jupiter
- 📐Input in AU, km, meters, or Earth radii
- ⚡Also computes orbital velocity for circular orbits
- 🆓Pure browser math — works instantly, no network needed
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Frequently Asked Questions
What is Kepler's Third Law?
Kepler's Third Law states that the square of an orbit's period is proportional to the cube of its semi-major axis: T² ∝ a³. For solar orbits: T (years) = a (AU)^1.5. For example, Mars at 1.52 AU has a period of 1.52^1.5 ≈ 1.88 years.
How low can an orbit be around Earth?
The lowest stable orbit around Earth is around 160 km altitude (LEO). At that altitude the orbital period is about 87.5 minutes and the orbital velocity is about 7.8 km/s.
What is a geostationary orbit?
A geostationary orbit has a period of exactly 24 hours, matching Earth's rotation. This requires an altitude of 35,786 km above the equator. At this height, a satellite appears fixed over one point on Earth.
Does this work for moons and satellites?
Yes — select 'Earth' as the central body for Earth satellites, or 'Jupiter' for Jupiter's moons. The formula works for any two-body system where one mass dominates.