Distance Length Unit Conversion Calculators
Convert Light Year DIstance units Calculator.
A light-year (symbol: ly), sometimes written light year or lightyear, is a unit of length used informally to express astronomical distances. It is approximately 10 trillion kilometres (or about 6 trillion miles).[note 1] As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year. Because it includes the word year, the term light-year is sometimes misinterpreted as a unit of time.