# Watts to lumens calculator

Electric power in watts (W) to luminous flux in lumens (lm) calculator and how to calculate.

Enter the power in watts, luminous efficacy in lumens per watt and press the *Calculate* button to get the luminous flux in lumens:

* the predefined luminous efficacy values are typical / average values.

## Watts to lumens calculation formula

The luminous flux *Î¦*_{V} in lumens (lm) is equal to the power P in watts (W), times the luminous
efficacy * Î·* in lumens per watt (lm/W):

*Î¦*_{V(lm)} = *P*_{(W)} Ã—* Î·*_{(lm/W)}

So

lumens = watts Ã— (lumens per watt)

or

lm = W Ã— (lm/W)

#### Example

What is the luminous flux of a lamp that has power consumption of 60 watts and luminous efficacy of 15 lumens per watt?

*Î¦*_{V} = 60 W Ã— 15 lm/W = 900 lm

## Luminous efficacy table

Light type | Typical luminous efficacy (lumens/watt) |
---|---|

Tungsten incandescent light bulb | 12.5-17.5 lm/W |

Halogen lamp | 16-24 lm/W |

Fluorescent lamp | 45-75 lm/W |

LED lamp | 80-100 lm/W |

Metal halide lamp | 75-100 lm/W |

High pressure sodium vapor lamp | 85-150 lm/W |

Low pressure sodium vapor lamp | 100-200 lm/W |

Mercury vapor lamp | 35-65 lm/W |

Energy saving lamps have high luminous efficacy (more lumens per watt).