How to use Power Converter
- Enter the Value in the unit you have, for example 1.
- Choose Convert from, such as Mechanical horsepower (hp).
- Choose Convert to, such as Kilowatts (kW).
- Leave Decimal places at 4, or pick another precision.
- The result, the watt row and the horsepower note update as you change the values.
Example: Power Converter
Convert mechanical horsepower to kilowatts.
Options
- Convert from
- Mechanical horsepower, metric horsepower and electrical horsepower are three separate entries, so the tool never assumes which one a bare hp figure meant.
- Decimal places
- Horsepower factors are long decimals, so four places is the default. Whole results ignore the setting and keep every digit.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
Three horsepower definitions, three numbers
Horsepower was coined for steam engines and later standardized in more than one way, so the word alone is ambiguous. Mechanical horsepower, common in the United States and the United Kingdom, is 550 foot-pounds force per second, or 745.6998715822702 W from the international foot and the standard pound force. Metric horsepower is 75 meter-kilogram force per second at standard gravity, exactly 735.49875 W, and shows up as PS in Germany and cv in some other countries. Electrical horsepower is exactly 746 W by definition. The page keeps them apart and prints the watt figure so the choice is visible.
NIST Special Publication 811, Appendix B.8: horsepower factors
Why standard gravity matters for metric horsepower
A metric horsepower is a weight lifted over a distance per second, so the definition has to state which gravity it uses. The standard value is exactly 9.80665 meters per second squared, which turns 75 meter-kilogram force per second into exactly 735.49875 W. Without that fixed gravity value the unit would drift with location, which is why the factor here is a definition rather than a measurement.
NIST Special Publication 811, Appendix B.8: standard acceleration of free fall
Questions about Power Converter
Is metric horsepower the same as mechanical horsepower?
No. Mechanical horsepower is 550 foot-pounds force per second, about 745.7 W. Metric horsepower, written PS or cv, is 75 meter-kilogram force per second, exactly 735.49875 W. The metric unit is roughly 1.4 percent smaller.
How many watts is one horsepower?
One mechanical horsepower is 745.6998715822702 W from its definition. One metric horsepower is 735.49875 W and one electrical horsepower is exactly 746 W. Pick the entry that matches your source.
Why is there a BTU per hour unit here?
BTU per hour is a rate of energy use, so it belongs with power units. It is not the same as a BTU, which is an amount of energy. One BTU per hour is about 0.293071 W.
Can power be negative?
Yes. A negative value simply describes power moving in the opposite direction, such as a solar inverter exporting to the grid. The size is unchanged by the sign.
Does this tell me the power of my appliance?
No. It converts a figure you already have. Appliance ratings vary by model and duty cycle, so read the nameplate or manual for the real number.