# Convert watts to hp

Please provide values below to convert watt [W] to horsepower (metric), or *vice versa*.

### Watt

**Definition:** A watt (Symbol: W) is the SI (International System of Units) derived unit of power. It is defined as 1 joule per second and is used to quantify the rate of energy transfer.

**History/origin:** The watt is named after James Watt, a Scottish inventor. It was first proposed in 1882 by William Siemens who defined it as "the power conveyed by a current of an Ampere through the difference of potential of a Volt." This was the definition used at the time within the existing system of units. In 1908, the "international" definitions were defined, with Siemens' definition being adopted as the international watt. These were used until 1948 when the General Conference on Weights and Measures re-defined the watt to absolute units, using only mass, time, and length. 1 absolute watt is equal to 1.00019 international watts. The absolute watt was adopted as the SI unit of power in 1960.

**Current use:** As the SI derived unit of power, the watt in all its multiples and submultiples is used in many applications worldwide from radio transmission to use in the electric power industry. The watt as a unit of power should not be confused with its energy counterpart, the watt-hour (and all its multiples/submultiples).

### Horsepower (metric)

**Definition:** The unit horsepower (symbol: hp) is a unit of measurement of power (the rate at which work is done). Mechanical horsepower, also known as imperial horsepower, is defined as approximately 745.7 watts (550 ft·lbf/s), while metric horsepower is approximately 735.5 watts (75 kgf·m/s). Boiler horsepower, albeit a less common measurement than either imperial or metric horsepower, is used for rating steam boilers, and is equivalent to 34.5 pounds of water evaporated per hour at 212 degrees Fahrenheit, or 9809.5 watts. In addition, when rating electric motors, one horsepower is equal to 746 watts.

**History/origin:** The term horsepower was adopted in the late 18^{th} century by James Watt to compare the output of steam engines with the power of draft horses. Watt was not the first person to compare the output of horses to that of engines. As early as 1702, Thomas Savery referenced horses when describing the output of an engine. It is believed that Watt built on this idea and introduced the term horsepower, largely in an effort to market his steam engine. The term was later expanded to include other types of output power such as the imperial and metric horsepower measurements commonly used today.

### Watt to Horsepower (metric) Conversion Table

Watt [W] | Horsepower (metric) |
---|---|

0.01 W | 1.35962E-5 horsepower (metric) |

0.1 W | 0.0001359622 horsepower (metric) |

1 W | 0.0013596216 horsepower (metric) |

2 W | 0.0027192432 horsepower (metric) |

3 W | 0.0040788649 horsepower (metric) |

5 W | 0.0067981081 horsepower (metric) |

10 W | 0.0135962162 horsepower (metric) |

20 W | 0.0271924323 horsepower (metric) |

50 W | 0.0679810809 horsepower (metric) |

100 W | 0.1359621617 horsepower (metric) |

1000 W | 1.3596216173 horsepower (metric) |

### How to Convert Watt to Horsepower (metric)

1 W = 0.0013596216 horsepower (metric)

1 horsepower (metric) = 735.49875 W

**Example:** convert 15 W to horsepower (metric):

15 W = 15 × 0.0013596216 horsepower (metric) = 0.0203943243 horsepower (metric)