Orbital Velocity Calculator
At 420 km above Earth a circular orbit needs a speed of 7.66129 km/s and takes about 92.8 minutes, close to the ISS’s real figures.
The ISS orbits at about 420 km.
7.66129213082409 km/s
Full answer, then cut to fewer decimals (not rounded):
- 7.66129213082409 km/s
- 7.6612921308240 km/s
- 7.661292130824 km/s
- 7.66129213082 km/s
- 7.6612921308 km/s
- 7.661292130 km/s
- 7.66129213 km/s
- 7.6612921 km/s
- 7.661292 km/s
- 7.66129 km/s
- 7.6612 km/s
- 7.661 km/s
- 7.66 km/s
- 7.6 km/s
- Orbital period T
- 92.82400995 min
- Orbital period
- 1.547066833 h
- Orbit radius r = R + altitude
- 6791 km
- In km/h
- 27580.65167 km/h
- Escape velocity at this altitude
- 10.83470324 km/s
Step-by-step solution
- r = R + h = 6371 km + 420 km = 6791 km
- v = √(GM ÷ r) = √(398600441800000 ÷ 6791000) = 7661.292131 m/s
- T = 2π √(r³ ÷ GM) = 5569.440597 s = 92.82400995 min
Orbital Velocity Formula
v = √(GM / r), T = 2π √(r³ / GM)
r = R + altitude, the distance from the body’s centre; GM the gravitational parameter
Worked Example
The International Space Station about 420 km above Earth:
- r = R + h = 6371 km + 420 km = 6791 km
- v = √(GM ÷ r) = √(398600441800000 ÷ 6791000) = 7661.292131 m/s
- T = 2π √(r³ ÷ GM) = 5569.440597 s = 92.82400995 min
Orbital period: 1.547066833 h · Orbit radius r = R + altitude: 6791 km · In km/h: 27580.65167 km/h · Escape velocity at this altitude: 10.83470324 km/s
Low Earth orbit
Below about 2000 km orbits take 88–127 minutes. The drag of the thin upper atmosphere slowly lowers them, which is why the ISS needs regular reboosts.
More Gravitation and Orbits Calculators
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Escape Velocity Calculator
vₑ = √(2GM / R)
G gravitational constant, M mass of the body, R distance from its centre (the radius at the surface)
Example: Escaping Earth from its surface (GM = 3.986004418 × 10¹⁴ m³/s², R = 6371 km): Escape velocity from Earth vₑ = 11.1861 km/s.
Frequently asked questions
What altitude gives a 24-hour orbit?
About 35,786 km above the equator (r = 42,164 km): the geostationary orbit, where satellites appear fixed in the sky.
Why do higher satellites move slower?
Gravity weakens with distance, so less speed is needed to stay in a circle, and the path is longer, so the period grows as r^1.5 (Kepler’s third law).
Sources
- CODATA Recommended Values of the Fundamental Physical Constants: 2018, National Institute of Standards and Technology .
- Planetary Fact Sheet, NASA Goddard Space Flight Center .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
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APA
Scientific Converters. (2026, October 15). Orbital Velocity Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/orbital-velocity-calculator/
IEEE
Scientific Converters, "Orbital Velocity Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/orbital-velocity-calculator/