What is milliwatt?
A milliwatt is a unit of power equal to one thousandth of a watt. It is used in low-power electronics, wireless communication systems, laser specifications, and medical device power ratings.
Real-world uses
Milliwatts measure the power of laser pointers (Class 1: <1 mW; Class 3B: up to 500 mW), Bluetooth radios (typically 1–100 mW), Wi-Fi transmitters, and fibre optic signals. They are used in optical communications, consumer electronics, and medical laser specifications.
History
Milliwatts became relevant as the miniaturisation era brought small electrical and optical devices into widespread use from the mid-20th century. Consumer electronics, telecommunications, and biomedical equipment all required power specifications at this sub-watt scale.
Common mistakes
Confusing milliwatts (mW) with microwatts (µW)—1 mW = 1,000 µW. Also, assuming all laser pointers operate at the same power level; safety regulations classify lasers by output power in mW, and even small increases can be hazardous to the eyes.
What is horsepower (mechanical)?
Mechanical horsepower is a traditional unit of power equal to approximately 745.7 watts. It is widely used in automotive and industrial contexts to express engine output, pump capacity, and motor ratings.
Real-world uses
Horsepower is used to rate car engines, industrial motors, lawn mowers, outboard boat motors, and air compressors in the United States and some other markets. A typical family car engine ranges from 100–300 hp. It is also used in aviation and marine propulsion ratings.
History
James Watt coined the term "horsepower" around 1782 to help customers understand the power of his steam engines by comparing it to draft horses. He calculated that a horse could perform work at a rate of about 33,000 foot-pounds per minute, which became the definition of one mechanical horsepower.
Common mistakes
There are at least three different definitions: mechanical horsepower (approximately 745.7 W), metric horsepower (735.5 W), and electrical horsepower (746 W). Automotive specifications often do not specify which type is used, and the differences matter when comparing international specifications.
When is this conversion used?
Converting between milliwatt and horsepower (mechanical) is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region.
Worked examples
1 milliwatt = 0.00000134 horsepower (mechanical)
1 horsepower (mechanical) = 745.69987158 watt
How to convert milliwatt to horsepower (mechanical)
To convert milliwatt to horsepower (mechanical), multiply the value by 0.00000134.
To convert horsepower (mechanical) back to milliwatt, multiply by 745,699.87158227.
Measurement standards
The watt is the SI derived unit of power, defined as one joule per second (kg·m²/s³). Horsepower remains in widespread informal use, particularly in the automotive industry, but has no single universal definition across regions.
Did you know?
The human body at rest produces about 80 watts of power — roughly enough to keep an incandescent light bulb glowing. During intense exercise, a trained cyclist can sustain over 400 watts, and elite sprinters briefly exceed 2,000 watts.
Quick reference: milliwatt to horsepower (mechanical)
| milliwatt | horsepower (mechanical) |
|---|---|
| 0.1 | 1.341022e-07 |
| 0.5 | 6.705110e-07 |
| 1 | 0.00000134 |
| 2 | 0.00000268 |
| 5 | 0.00000671 |
| 10 | 0.00001341 |
| 25 | 0.00003353 |
| 50 | 0.00006705 |
| 100 | 0.0001341 |
| 250 | 0.00033526 |
| 500 | 0.00067051 |
| 1,000 | 0.00134102 |
Common values
| milliwatt | horsepower (mechanical) | |
|---|---|---|
| LED light bulb | 10,000 milliwatt | 0.01341022 horsepower (mechanical) |
| Desktop computer | 300,000 milliwatt | 0.40230663 horsepower (mechanical) |
| Microwave oven | 1,000,000 milliwatt | 1.34102209 horsepower (mechanical) |
| Small car engine | 75,000,000 milliwatt | 100.57665672 horsepower (mechanical) |
| Wind turbine (large) | 3.000000e+09 milliwatt | 4,023.06626879 horsepower (mechanical) |
Available Power units
More milliwatt conversions
- Convert milliwatt to watt
- Convert milliwatt to kilowatt
- Convert milliwatt to horsepower (mechanical)
- Convert milliwatt to megawatt
- Convert milliwatt to gigawatt
- Convert milliwatt to microwatt
- Convert milliwatt to BTU per hour
- Convert milliwatt to kilocalorie per hour
- Convert milliwatt to ton of refrigeration
Assumption: horsepower values use mechanical horsepower.