**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 1.0570008340246E-16 light-year.

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

You can use this form to select from known units:

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 X unit

light-year to dekametre

light-year to faden [Switzerland]

light-year to pace [great]

light-year to myriametre

light-year to stadium

light-year to elle [Vienna]

light-year to pe [Portuguese]

light-year to mile [survey]

light-year to t'sun