**Full name:** light year

**Plural form:** light years

**Symbol:** ly

**Alternate spelling:** lightyear

**Category type:** length

**Scale factor:** 9460730472580800

The SI base unit for length is the metre.

1 metre is equal to 1.05700083402E-16 light year.

Valid units must be of the **length** type.

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A light year, abbreviated ly, is the distance light travels in one year: roughly 9.46 × 1012 kilometres (9.46 petametres, or about 5.88 × 1012 (nearly six trillion) miles). More specifically, a light year is defined as the distance that a photon would travel, in free space and infinitely far away from any gravitational or magnetic fields, in one Julian year (365.25 days of 86400 seconds each).

light year to pe [Portuguese]

light year to li [imperial China]

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light year to miglio

light year to foot

light year to kilometre

light year to decimetre

light year to pace [Roman]

light year to kiloparsec