Power Converter
Convert between watts, kilowatts, megawatts, both kinds of horsepower and BTU per hour.
Runs entirely in your browser. Nothing is uploaded, logged or stored.
100 kW
135.9622 PS
Metric horsepower
In every unit
| Unit | Symbol | Value |
|---|---|---|
| Watt | W | 100,000 |
| Milliwatt | mW | 100,000,000 |
| Kilowatt | kW | 100 |
| Megawatt | MW | 0.1 |
| Gigawatt | GW | 0.0001 |
| Metric horsepower | PS | 135.9622 |
| Mechanical horsepower | hp | 134.1022 |
| BTU per hour | BTU/h | 341,214.2 |
| Foot-pound per second | ft·lb/s | 73,756.21 |
| Calorie per second | cal/s | 23,900.57 |
Power is the rate at which energy is used, not the amount of it. A kettle rated 2000 watts draws two kilowatts for as long as it is on; how much that costs depends on how long, which is energy. This page converts the rate.
It also keeps the two horsepowers apart, because they are not the same unit and the difference is large enough to notice on a specification sheet.
How it works
Every unit is expressed in watts and conversions go through them. One watt is one joule per second, and the prefixes are the ordinary decimal ones.
The two horsepowers come from two different definitions that were never reconciled. Metric horsepower, written PS or ch or CV, is the power needed to lift 75 kilograms one metre in one second: exactly 735.49875 watts. Mechanical horsepower, written hp, is 550 foot-pounds-force per second: about 745.7 watts. A car quoted at 300 hp and one quoted at 300 PS differ by roughly four horsepower, which is why the unit matters as much as the number.
BTU per hour is the air-conditioning and heating unit. It is an energy unit divided by a time, so one BTU per hour is 1055.05585262 joules spread over 3600 seconds — about 0.293 watts.
Examples
| Case | Input | Result |
|---|---|---|
| A metric horsepower | 1 PS | 735.4988 W |
| An imperial horsepower, which is not the same unit | 1 hp | 745.6999 W |
| A motor rated in kilowatts | 100 kW | 135.9622 PS |
Frequently asked questions
Which horsepower does a car manufacturer mean?
It depends where the figure was published. European and Japanese makers quote metric horsepower, written PS, ch or CV; British and American ones quote mechanical horsepower, written hp or bhp. Both are in the list here under their own definitions rather than merged into an average.
Is a kilowatt the same as a kilowatt-hour?
No, and the distinction is the whole point. A kilowatt is a rate; a kilowatt-hour is the amount of energy that rate delivers in an hour. Your appliance is rated in kilowatts and your bill is in kilowatt-hours. The kilowatt-hour lives on the energy converter, not here.
Why is my air conditioner rated in BTU?
It is rated in BTU per hour, usually shortened to BTU in marketing, which is a rate of heat moved. A 12,000 BTU unit is about 3.5 kilowatts of cooling. Note that this is the heat it moves, not the electricity it draws — those are different numbers and the ratio between them is the efficiency rating.
Can I convert dBm here?
No. Decibel-milliwatts are logarithmic: adding 10 dBm multiplies the power by ten rather than adding a fixed amount. Every unit on this page is related to every other by a constant factor, and dBm is not, so including it would produce wrong answers in a familiar-looking table.
Good to know
- Every factor used here is an exact definition rather than a rounded measurement, so the only error in a result is the one that comes from displaying it with a finite number of digits.