Horsepower to Milliwatts (hp to mW)
1 horsepower equals 745,699.8716 milliwatts (rounded).
How to convert horsepower to milliwatts
To convert horsepower to milliwatts, multiply the number of horsepower by 745,699.8716. The factor is rounded to 10 significant digits. To go the other way, multiply milliwatts by 0.00000134102209 (rounded).
milliwatts = horsepower × 745,699.8716
Example: 10 horsepower = 7,456,998.716 milliwatts.
Several different horsepower units exist. This site lists mechanical (745.7 W), metric (735.5 W) and electrical (746 W) horsepower separately.
About these units
Horsepower (hp)
The mechanical horsepower: 550 foot-pounds per second, about 745.7 watts. James Watt coined it to compare steam engines with draft horses.
Horsepower was a sales pitch before it was a unit. Late in the 18th century the Scottish engineer James Watt adopted the term to compare the output of steam engines with the draft horses they replaced. His 1782 experiments found that a brewery horse could produce 32,400 foot-pounds-force per minute, and in 1783 he and Matthew Boulton standardized the figure at 33,000 foot-pounds-force per minute. Customers could then be told how many horses an engine would replace.
That figure works out to 550 foot-pounds-force per second, or about 745.7 watts: the power needed to lift 550 pounds by one foot in one second. Several cousins exist, including metric horsepower and electrical horsepower, defined as exactly 746 W. Car ratings added more confusion. Early British taxable horsepower was a formula based on bore and cylinder count, not measured output, and American ratings before 1972 used SAE gross brake horsepower, measured without accessories. In the European Union, horsepower may be used only as a supplementary unit under Directive 80/181/EEC, in force from 1 January 2010.
1 horsepower = 745.6998716 watts (approximately).
Sources: Wikipedia: Horsepower; Wikipedia: Metric horsepower
Milliwatt (mW)
One thousandth of a watt. Used for lasers and small electronics.
A thousandth of a watt sounds negligible, but it is the working scale for a great deal of light and signal technology. A common laser pointer emits about five milliwatts of light, and a hearing aid draws less than one. The watt is named for James Watt, with the name proposed by C. William Siemens in 1882 and the unit placed in the SI by the General Conference on Weights and Measures in 1960, and the milliwatt simply applies the standard milli prefix to it.
Radio and audio engineers use the milliwatt as a zero point. A level in dBm is a power measured in decibels relative to one milliwatt, so 0 dBm is exactly 1 mW and each 10 dB step multiplies or divides the power by ten. One milliwatt is 0.001 watt, 1,000 microwatts, and 10,000 ergs per second in the older CGS system, since one watt equals 10 million ergs per second.
1 milliwatt = 0.001 watts (exactly).
Sources: Wikipedia: Watt
Related conversions
- Milliwatts to horsepower (reverse)
- Horsepower to watts
- Horsepower to kilowatts
- Horsepower to megawatts
- Horsepower to gigawatts
- Horsepower to metric horsepower
- Horsepower to BTU per hour
- Horsepower to electrical horsepower
- Horsepower to foot-pounds per second
- Horsepower to tons of refrigeration
- Horsepower to kilocalories per hour
- Horsepower to calories per second
- Horsepower to ergs per second
- Watts to milliwatts
- Kilowatts to milliwatts
See all power units.