Calculate circular orbital velocity, period, and escape velocity for any altitude around Earth, Mars, Moon, Jupiter, Sun, or a custom body. Includes orbit types reference.
For any circular orbit, there is exactly one speed at which gravitational acceleration provides the centripetal force needed to maintain constant altitude: v = √(GM/r). This orbital velocity — along with period, escape velocity, and orbital energy — defines the physics of spaceflight, satellite networks, and planetary science.
This Orbital Velocity Calculator computes circular orbit parameters for Earth, Moon, Mars, Jupiter, the Sun, or any custom body. Enter the altitude and satellite mass to obtain orbital velocity, period, escape velocity, gravitational acceleration, and kinetic energy. Presets cover the ISS, GPS constellation, geostationary orbit, and Moon orbit, and a complete orbit types reference table provides context.
Students, space enthusiasts, aerospace engineers, and educators use this calculator to explore how altitude, body mass, and body radius determine orbital dynamics — the foundation of all astrodynamics. Check the example with realistic values before reporting. Use the steps shown to verify rounding and units. Cross-check this output using a known reference case.
Orbital mechanics is fundamental to satellite design, mission planning, and understanding our solar system. This calculator makes it easy to compare orbit types, estimate delta-v requirements, and explore what-if scenarios across different celestial bodies. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Orbital Velocity (circular): v = √(GM / r) Orbital Period: T = 2πr / v Escape Velocity: v_esc = √(2GM / r) = v_orb × √2 Gravitational Acceleration at orbit: a = GM / r² Specific Orbital Energy: ε = −GM / (2r) Where: G = 6.674 × 10⁻¹¹ N·m²/kg² M = central body mass (kg) r = R_body + altitude (m) R_body = body radius (m)
Result: v ≈ 7.67 km/s, T ≈ 92.4 min
The ISS orbits at 400 km altitude (r = 6,771 km from Earth center). At this radius, v = √(GM/r) = 7,672 m/s. The period is 2πr/v ≈ 5,540 s ≈ 92 min. Escape velocity is 10.85 km/s — about 41% higher than orbital speed.
Kepler's third law relates orbital period to semi-major axis: T² ∝ a³. For circular orbits (a = r), this simplifies to T = 2π√(r³/GM). This law allows calculating the orbit of any body if you know the central mass. Newton showed that Kepler's empirical laws follow directly from universal gravitation.
Changing from one orbit to another requires a velocity change (delta-v). The most fuel-efficient way to transfer between two circular orbits is the Hohmann transfer — two engine burns separated by half an elliptical orbit. The delta-v from LEO to GEO is about 3.9 km/s, which is why geostationary satellites need such large upper stages.
Satellites in low Earth orbit experience atmospheric drag that gradually reduces their altitude and speed (paradoxically, they speed up as they descend to orbits where orbital velocity is higher). The ISS requires periodic reboosts (about 7 km/year altitude loss without correction). Above ~1,000 km, drag is negligible and orbits are stable for centuries.
Gravity weakens with distance (1/r²), so less centripetal acceleration is needed at higher altitudes. Since v = √(GM/r), velocity decreases as the square root of the increasing orbital radius.
Orbital velocity maintains a circular orbit; escape velocity is the speed needed to leave the gravitational field entirely. Escape velocity is always √2 ≈ 1.414 times the circular orbital velocity at the same altitude.
The ISS orbits at about 7.67 km/s (27,600 km/h or 17,150 mph) at an altitude of approximately 400 km. It completes one orbit every ~92 minutes.
Geostationary orbit (GEO) is at 35,786 km altitude, where the orbital period matches Earth rotation (23 h 56 m). The satellite appears stationary relative to the ground.
No. Orbital velocity depends only on the central body mass and the orbital radius. All objects at the same altitude orbit at the same speed regardless of their mass — this is why astronauts experience weightlessness.
In theory, yes, but practically the orbit must be above the atmosphere (>160 km for Earth) and below gravitational influence limits. Low orbits experience atmospheric drag and decay without station-keeping.