Convert between astronomical units, kilometers, miles, light-years, and parsecs. Includes planet presets, solar system scale chart, and distance table.
The astronomical unit (AU) is the mean distance from the Earth to the Sun — exactly 149,597,870.7 kilometers by the 2012 IAU definition. It serves as the fundamental yardstick for measuring distances within the solar system. One AU is about 93 million miles, or roughly 8.3 light-minutes.
This converter translates between AU and five other distance scales: kilometers, miles, light-years, parsecs, and solar radii. Planet presets let you instantly load the mean orbital distance of any planet from Mercury to Pluto, and a visual solar system scale shows how your distance compares to each orbit.
Whether you are a student calculating planetary distances for an astronomy class, a space enthusiast following a NASA mission, or a science writer translating AU figures into more intuitive units for readers, this tool provides every conversion you need alongside a comprehensive distance table covering the entire solar system and beyond. It also helps readers translate mission updates and orbital data into units they can intuitively compare.
AU figures are commonly cited in astronomy news and textbooks, but most people lack intuition for how far 1 AU actually is. This converter bridges that gap by providing kilometers, miles, and light-travel-time simultaneously. The planet presets and scale chart make solar system distances tangible for classroom learning, science communication, and mission tracking.
1 AU = 149,597,870.7 km = 92,955,807.3 mi 1 AU ≈ 8.317 light-minutes 1 light-year = 63,241.077 AU 1 parsec = 206,265 AU
Result: 778.5 million km
Jupiter orbits at 5.203 AU from the Sun. That is 5.203 × 149,597,870.7 = 778,479,120 km, or about 43.3 light-minutes.
Astronomers have estimated the Earth–Sun distance since antiquity. Aristarchus of Samos (3rd century BCE) attempted a geometric calculation, arriving at ~20× the Earth–Moon distance (the true value is ~390×). Accurate measurements became possible in the 17th–18th centuries via transits of Venus. The AU was formalized by the IAU in 1976 and redefined as an exact metric value in 2012.
NASA and ESA use AU to express distances in mission design documents. For example, the James Webb Space Telescope orbits at the L2 Lagrange point, about 0.01 AU (1.5 million km) from Earth. Mars missions deal with a varying Earth–Mars distance of 0.37–2.68 AU, which affects communication delay (4–24 minutes round trip).
For interstellar distances, AU becomes impractical. Proxima Centauri at 268,770 AU is better expressed as 4.24 light-years or 1.3 parsecs. However, AU remains essential for expressing exoplanet orbital distances — for example, an exoplanet at 0.05 AU is a "hot Jupiter" orbiting extremely close to its star.
Since 2012, the IAU defines 1 AU as exactly 149,597,870,700 meters (about 93 million miles). It approximately equals the mean Earth–Sun distance.
149,597,870.7 km, or roughly 150 million km. This exact value is fixed by IAU definition and does not vary with Earth's orbital position.
About 499 seconds, or 8 minutes and 19 seconds. This value is commonly used to estimate communication delay between Earth and near-solar-system spacecraft.
A light-year (9.46 trillion km) is about 63,241 AU. Light-years are used for interstellar distances, while AU is used within the solar system.
A parsec is the distance at which 1 AU subtends an angle of 1 arcsecond. 1 pc ≈ 3.26 light-years ≈ 206,265 AU.
Pluto's mean distance from the Sun is about 39.5 AU, though its eccentric orbit ranges from 29.7 to 49.3 AU.