ISS by the Numbers: Key Facts and Figures

The International Space Station is an engineering achievement that is hard to fully appreciate without looking at the numbers. Here are the key facts and figures that define life and operations on the station.

Size and structure

• Total mass: approximately 420,000 kg (925,000 lb) - about the same as 280 cars
• Pressurized volume: 916 cubic meters - roughly the interior space of a Boeing 747
• End-to-end length: 109 meters (357 feet) - about the length of a football field including end zones
• Solar array wingspan: 73 meters (240 feet)
• Number of modules: 16 pressurized modules from five different countries

Orbit

• Altitude: 400 to 420 km (250 to 260 miles) above Earth's surface
• Orbital speed: 27,600 km/h (17,150 mph) - about 7.66 km per second
• Orbital period: approximately 90 minutes per orbit
• Orbits per day: about 16, meaning the crew sees 16 sunrises and 16 sunsets every day
• Orbital inclination: 51.6 degrees - this allows the station to pass over most of Earth's populated areas

Power

• Solar array area: about 2,500 square meters (27,000 square feet)
• Power generation: up to 215 kilowatts from the solar arrays
• Usable power: about 90 kilowatts available for station systems and experiments
• Battery type: lithium-ion (replaced the original nickel-hydrogen batteries in 2019-2021)

Life support

• Water recycled: approximately 3,600 liters per crew member per year
• Oxygen generated: about 6 kg per day via electrolysis (splitting water into hydrogen and oxygen)
• CO2 removed: by the Carbon Dioxide Removal Assembly, which scrubs about 5 kg of CO2 per day
• Cabin pressure: ~760 mmHg (sea level equivalent)
• Cabin temperature: 22-24 degrees C (72-75 degrees F)

Crew and operations

• Continuous habitation: since November 2, 2000 - over 25 years
• Total crew members: more than 270 people from 21 countries have visited
• Typical crew size: 6-7 people
• Expedition duration: about 6 months per crew rotation
• Spacewalks: more than 260 conducted for assembly and maintenance
• Scientific experiments: over 3,000 investigations across all disciplines

Cost

• Total cost: estimated at over $150 billion, making it the most expensive single object ever built
• Annual operating cost: approximately $3-4 billion (NASA's share)
• Cost to launch 1 kg: roughly $20,000 (varies by vehicle)

The station is currently expected to operate until 2030, after which NASA plans a controlled deorbit using a dedicated spacecraft. In its three decades of service, the ISS has served as a laboratory, observatory, factory, and a model for international cooperation in space exploration.