# Radian

The **radian**, denoted by the symbol **rad**, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. The unit was formerly an SI supplementary unit (before that category was abolished in 1995).[1] The radian is defined in the SI as being a dimensionless unit, with 1 rad = 1.[2] Its symbol is accordingly often omitted, especially in mathematical writing.

Radian | |
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General information | |

Unit system | SI |

Unit of | angle |

Symbol | rad |

Conversions | |

1 rad in ... | ... is equal to ... |

milliradians | 1000 mrad |

turns | 1/2π turn |

degrees | 180/π° ≈ 57.296° |

gradians | 200/π grad ≈ 63.662^{g} |