The distance between the Earth and the International Space Station (ISS) - although at a nearly circular orbit - varies over time, as the ISS orbits the Earth at a nominal altitude of about 400 kilometers (250 miles) above the surface of the Earth.
At its closest approach, the ISS can be as close as about 370 kilometers (230 miles) from the Earth. At its farthest distance, the ISS can be about 460 kilometers (290 miles) from the Earth.
To give you a sense of scale, the ISS orbits the Earth about once every 90 minutes, traveling at a speed of about 28,000 km/h (17,500 mph). This means that it takes about 90 minutes for the ISS to complete one orbit around the Earth and return to its starting point.
It is also worth noting that the distance between the Earth and the ISS can be measured in a variety of units, including kilometers, miles, and AU. The value will depend on the unit of measurement used, information of which can be found in the Distance units in space section of apostaseis.gr.