ISS Facts: Size, Speed, Altitude, Orbit & Crew
The International Space Station (ISS) is a crewed research laboratory about the size of a football field. It orbits Earth at roughly 400–420 km altitude at about 27,600 km/h, completing one lap every 92–93 minutes (about 15.5 orbits a day) on an orbit inclined 51.6° to the equator. It has been continuously crewed since 2 November 2000, usually by about seven people.
Live values at build time
- Orbit-average altitude: about 420 km (height above the surface at this moment: 428 km).
- Speed: 27,570 km/h (7.66 km/s).
- Orbital period: 93.0 minutes, 15.49 orbits per day.
- Inclination: 51.6°.
- People aboard: 7.
Snapshot taken 2026-10-19 06:04 UTC. The live view replaces this as soon as the page’s script loads.
The key numbers
| Fact | Value | Notes |
|---|---|---|
| Length | 109 m (357 ft) | About the length of an American football field including end zones. |
| Width (solar arrays) | 73 m (240 ft) | Across the main truss and solar arrays. |
| Mass | ≈420,000 kg | About 925,000 lb, assembled in orbit from modules launched separately. |
| Altitude (average) | 400–420 km | Average height of the orbit. The height above the surface varies by about 10 km around each lap because Earth is slightly flattened, and drag slowly lowers the orbit until it is boosted back up. |
| Speed | ≈27,600 km/h | About 7.66 km/s (17,100 mph), relative to Earth’s centre. |
| Orbital period | ≈92–93 min | Time for one complete lap of the Earth. |
| Orbits per day | ≈15.5 | Sunrise or sunset is seen about 16 times every 24 hours. |
| Inclination | 51.6° | The highest latitude the station passes over, north or south. |
| Crew | About 7 | Normally about seven; more during short handovers. |
| Continuously crewed since | 2 Nov 2000 | The first long-duration crew, Expedition 1, arrived on this date. |
| Partner agencies | 5 | NASA (US), Roscosmos (Russia), ESA (Europe), JAXA (Japan), CSA (Canada). |
Altitude, speed, period, orbits per day and inclination update from the station’s current orbital elements when this page loads.
Key dates
- 20 Nov 1998Zarya, the first module, is launched, beginning assembly.
- 2 Nov 2000Expedition 1 arrives; humans have lived aboard continuously ever since.
- 2011Assembly of the main US-led segment is completed.
- 2020The first crewed flight of a commercial US spacecraft, SpaceX’s Crew Dragon, carries astronauts to the station.
- About 2030Planned end of operations, followed by a controlled re-entry over a remote ocean area. Read what happens after 2030.
The numbers explained
Why so fast? At 400 km up gravity is still about 90% as strong as on the ground. The station does not escape gravity; it is in constant free fall around the Earth, moving sideways fast enough that it keeps missing the surface. That sideways speed is the 27,600 km/h. See how fast the ISS travels.
Why does the altitude change? Even at 400 km there are traces of atmosphere, and the drag they cause slowly lowers the orbit. Visiting spacecraft periodically fire their engines to raise it again, and the station can also manoeuvre to avoid debris. See how high the ISS orbits.
Why 51.6 degrees? The inclination was chosen so that rockets from Russia’s launch sites, as well as those from the US and others, could reach it. It means the station passes over most of the inhabited world, but never above 51.6° north or south. See the ISS orbit explained.
Can I see it? Yes. On the best passes it outshines every star and can rival Venus, but it is only visible at dawn and dusk, when it is sunlit and your sky is dark. Find your next pass with the visible-tonight finder or the pass times for 33 cities, and see where it is right now on the live map.
Frequently asked questions
How big is the International Space Station?
About 109 metres (357 feet) long and 73 metres (240 feet) wide across its solar arrays, roughly the size of a football field, with a mass of about 420,000 kilograms.
How fast does the ISS travel?
About 7.66 kilometres per second, or roughly 27,600 km/h (17,100 mph), which is why it circles the Earth about 15.5 times a day.
How high does the ISS orbit?
Roughly 400 to 420 kilometres (250 to 260 miles) above the surface. Drag slowly lowers it, so it is boosted periodically.
How many people live on the ISS?
Normally about seven, rising briefly during crew handovers. People have lived aboard continuously since 2 November 2000. See who is aboard right now.
When will the ISS be retired?
NASA and its partners plan to operate it until around 2030, then bring it down in a controlled re-entry over a remote part of the ocean.
Sources
Dimensions, mass, crew history and partner agencies are from NASA’s published ISS fact sheets. Altitude, speed, period, orbits per day and inclination are calculated live from the station’s current two-line orbital elements supplied by CelesTrak; see About & methodology for how.
Watch the station move in real time, with its ground track and the next pass over your location.
Open the live tracker Who is on board?