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Convert Light Year to Kilometer (ly to km) instantly with accurate, readable results.
Use our Length Unit Converter to quickly convert between meters, kilometers, feet, inches, miles, and more. This powerful unit conversion tool supports both metric and imperial systems, making it ideal for travel, engineering, education, and everyday use. Whether you're calculating distances or comparing measurements, our length unit conversion calculator ensures fast and accurate results every time.
Light-year (ly) - astronomical distance
Light-year is an astronomical distance equal to the distance light travels in vacuum in one Julian year. Used for interstellar and intergalactic scales; based on c = 299,792,458 m/s and a Julian year of 365.25 days (31,557,600 s)
- Symbol: ly
- System: Astronomical (non-SI, accepted for use with SI)
- Defined relation: 1 ly = c × 31,557,600 s = 9.4607304725808×10^15 m ≈ 9.4607×10^12 km
- Other relations: 1 ly ≈ 63,241.077 AU; 1 ly ≈ 0.306601 pc; 1 pc ≈ 3.26156 ly
- Typical examples: Proxima Centauri ~4.2465 ly; Milky Way diameter ~1.0×10^5 ly; Andromeda Galaxy ~2.5×10^6 ly
Kilometer (km) — SI unit of length equal to 1,000 meters
Used worldwide for road distances, mapping, and athletics. In the metric system it scales cleanly with meters and centimeters for everyday to large-scale measurements.
- Symbol: km
- System: SI derived unit
- Exact relations: 1 km = 1,000 m = 10⁵ cm = 10⁶ mm
- Imperial/US equivalents: 1 km ≈ 0.621371 mi ≈ 3,280.8399 ft ≈ 1,093.6133 yd
- Typical examples: intercity travel; 5 km and 10 km races