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Most of the time, the International Space Station (ISS) is orbiting the Earth at an altitude of approximately 220 miles (354 km), which places it in low Earth orbit (LEO). This distance can change, however, and has varied from 205 miles (330 km) to a planned maximum of 248 miles (400 km).
There are 24 hours in a day, therefore the ISS revolves around the Earth approximately 16 times per day. The number varies very slightly because it is based upon orbital altitude. When the ISS is closer to the Earth, it orbits more quickly and when the ISS is farther from the Earth, it orbits more slowly.