The orbital speed of the ISS is approximately 28,000 kilometers per hour. At that speed, the station circles Earth about once every 93 minutes and completes roughly 15 to 16 orbits in a day.
The ISS must travel so fast because it is continuously falling around Earth. Gravity pulls it downward, while its enormous sideways velocity carries it forward; together, these effects create a stable orbit rather than a direct plunge toward the planet.
The station travels prograde, meaning west to east, in the same general direction as Earth’s rotation. Its nearly circular orbit lies about 370 to 460 kilometers above Earth, though the exact altitude changes as atmospheric drag lowers the orbit and reboost maneuvers raise it.
People sometimes confuse orbital speed with the ISS’s speed relative to the ground or with the speed of individual spacecraft during docking. The station’s average orbital speed is the standard figure used for this quiz fact, and 28,000 kilometers per hour is the accepted rounded value.