Circular Orbital Speed Calculator

About this calculator

For a satellite in a stable circular orbit, gravity must supply exactly the centripetal force needed to keep it moving in a circle, and solving that balance gives v = √(GM/r), where GM is the standard gravitational parameter of the central body (Earth's is about 3.986×10¹⁴ m³/s²) and r is the orbital radius measured from the body's center, not its surface.

This equation is basic astrodynamics: it shows why low orbits require higher speeds than high ones (v shrinks as r grows), why the International Space Station at roughly 400 km altitude travels near 7.66 km/s, and why geostationary satellites at about 35,786 km altitude move much slower — around 3.07 km/s — while still completing one orbit every 24 hours because of the much larger circle they trace.