Enter the value and choose from watts, kilowatts, mechanical horsepower, metric horsepower and BTU per hour. Take the value from an appliance label, an engine specification or a heater rating. One mechanical horsepower is about 745.7 watts, and one metric horsepower is about 735.5 watts.
Power is a rate, so do not confuse it with energy units such as kilowatt-hours.
Power Converter: worked example
| Power to convert | 1 |
|---|---|
| Starting unit | Horsepower (mechanical) |
| Requested unit | Kilowatts |
| Converted value | 0.746 |
| 1 unit of "from" in "to" units | 0.746 |
Power Converter: formula
Common error: Confusing power with energy. Watts measure the rate of use and kilowatt-hours measure the total, so a 1,000 watt device running an hour uses one kilowatt-hour.
Rated power is not continuous consumption. Mechanical and metric horsepower differ, so match the selected unit to the specification. Electrical horsepower is defined as 746 watts.
A ton of air conditioning is a heat-transfer rate of 12,000 BTU per hour, not electrical input; BTU alone is energy.
Power Converter: changing Power to convert
| Power to convert | Converted value | 1 unit of "from" in "to" units |
|---|---|---|
| 0.8 | 0.597 | 0.746 |
| 0.9 | 0.671 | 0.746 |
| 1 (example) | 0.746 | 0.746 |
| 1.1 | 0.82 | 0.746 |
| 1.2 | 0.895 | 0.746 |
Power Converter: compare input ranges
| Input | Tested from | To | Converted value: low input | Converted value: high input | Swing |
|---|---|---|---|---|---|
| Starting unit | Watts | BTU per hour | 0.001 | 0.00029 | 0.00071 (134%) |
| Requested unit | Watts | BTU per hour | 745.7 | 2,544.4 | 1,798.7 (341114%) |
| Power to convert | 0.9 | 1.1 | 0.671 | 0.82 | 0.149 (20%) |
Power Converter: individual input comparisons
| Input | Value | Converted value | 1 unit of "from" in "to" units |
|---|---|---|---|
| Power to convert | 0.8 | 0.597 | 0.746 |
| 0.9 | 0.671 | 0.746 | |
| 1 | 0.746 | 0.746 | |
| 1.1 | 0.82 | 0.746 | |
| 1.2 | 0.895 | 0.746 | |
| Starting unit | Watts | 0.001 | 0.001 |
| Kilowatts | 1 | 1 | |
| Horsepower (mechanical) | 0.746 | 0.746 | |
| Horsepower (metric) | 0.735 | 0.735 | |
| BTU per hour | 0.00029 | 0.00029 | |
| Requested unit | Watts | 745.7 | 745.7 |
| Kilowatts | 0.746 | 0.746 | |
| Horsepower (mechanical) | 1 | 1 | |
| Horsepower (metric) | 1 | 1 | |
| BTU per hour | 2,544.4 | 2,544.4 |
Power Converter: which assumptions move the result?
Power Converter: values and definitions
| Quantity and definition | Value used |
|---|---|
| Power to convert | 1 |
| Starting unit — Unit to convert from. | Horsepower (mechanical) |
| Requested unit — Unit to convert to. | Kilowatts |
| Converted value | 0.746 |
| 1 unit of "from" in "to" units | 0.746 |
Unit Conversion calculators: Height Converter Calculator, Angle Converter Calculator, Data Rate Converter Calculator, Force Converter Calculator, Torque Converter Calculator, Frequency Converter Calculator.
Power ratings look different for the same job. A car lists horsepower, a heater lists BTU per hour, an appliance lists watts. One mechanical horsepower is about 745.7 watts, so a 1 horsepower motor draws roughly three quarters of a kilowatt.
Putting them in one unit lets you compare a generator against everything it has to run. Reference values: one kilowatt is about 1.34 mechanical horsepower and 3,412 BTU per hour. A metric horsepower is about 735.5 watts, so 100 mechanical horsepower is about 74.6 kilowatts and 100 metric horsepower about 73.5.
Pick mechanical or metric horsepower to match the source. The two differ by about 1.4 percent, which matters for precise sizing.
Convert energy on the energy converter, and torque on the torque converter. The watts to amps calculator relates power to current, the voltage drop page covers wiring, and the fuel economy converter relates to engine use. The Ohm's law calculator gives power from voltage and current.
How many BTU per hour is a kilowatt?
About 3,412 BTU per hour, so a 1.5 kilowatt heater delivers roughly 5,100 BTU per hour.
How many watts are in a horsepower?
About 745.7 watts for mechanical horsepower and about 735.5 watts for metric horsepower.
What is the difference between power and energy?
Power is the rate of using energy, in watts, while energy is the total used, in joules or kilowatt-hours.