Power Conversion Calculator
Free online Power Conversion Calculator to convert between watts, kilowatts, horsepower, and BTU/hr.
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The Power Conversion Calculator converts instantly between watts, kilowatts, megawatts, horsepower, and BTU per hour. Whether you're matching an engine's horsepower to a kilowatt rating or comparing an air conditioner's BTU output to its electrical draw, you get an exact answer in one click.
Why Power Units Need Converting
Power is measured differently across industries. Electricians speak in watts and kilowatts, the auto world uses horsepower, and HVAC equipment is rated in BTU per hour. When you need to compare a generator to appliances, or an engine to a motor, those mismatched units get in the way. This calculator bridges them with precise factors so the numbers line up.
How to Convert
- Enter the value you want to convert.
- Select the from and to units.
- Read the converted result instantly.
Common Power Conversions
| From | To | Factor |
|---|---|---|
| 1 horsepower (mechanical) | watts | ≈ 745.7 W |
| 1 kilowatt | horsepower | ≈ 1.341 hp |
| 1 kilowatt | BTU/hr | ≈ 3,412 BTU/hr |
| 1 megawatt | kilowatts | 1,000 kW |
The kW vs. kWh Confusion
One distinction trips people up constantly: kilowatts measure power, kilowatt-hours measure energy. Power is the rate at an instant; energy is power accumulated over time. A 2 kW heater running for three hours consumes 6 kWh. This tool converts power units to one another — for energy over time, multiply power by hours separately.
Mechanical vs. Metric Horsepower
Horsepower isn't a single value. Mechanical (imperial) horsepower is about 745.7 W, while metric horsepower (PS), common in European car specs, is about 735.5 W. The gap is small but real, so when precision matters, confirm which standard a datasheet uses before converting.
Who Relies on This
- Electricians matching loads and supply ratings.
- Mechanics and car buyers comparing hp and kW.
- HVAC pros sizing heating and cooling by BTU and watts.
- Engineers reconciling specs across unit systems.
Accurate and Free
Conversions use exact factors and full precision, all in your browser. Convert as often as you need, free.
Frequently Asked Questions
What units does the power converter support?
It handles the common power units: watts (W), kilowatts (kW), megawatts (MW), horsepower (hp), and BTU per hour. These cover electrical, mechanical, and heating/cooling contexts in one place.
How many watts are in one horsepower?
One mechanical horsepower equals about 745.7 watts, or roughly 0.746 kilowatts. So a 100-hp engine produces approximately 74.6 kW. The calculator applies the exact factor so you don't have to remember it.
Why convert between watts and BTU/hr?
Heating and cooling equipment is often rated in BTU per hour, while electrical draw is in watts. Converting between them lets you compare an air conditioner's cooling capacity with its power consumption, or size equipment correctly.
What's the difference between kW and kWh?
Kilowatts (kW) measure power — the rate of energy use at an instant. Kilowatt-hours (kWh) measure energy — power used over time. A 2 kW heater running for 3 hours uses 6 kWh. This tool converts power units, not energy.
Is metric horsepower different from mechanical horsepower?
Slightly. Mechanical (imperial) horsepower is about 745.7 W, while metric horsepower (PS) is about 735.5 W. The difference is small but matters in precise engineering, so confirm which standard a spec uses.
Who needs a power converter?
Engineers, electricians, mechanics, HVAC professionals, and anyone comparing equipment specs across different unit systems — for example, matching a generator's kW rating to appliances rated in watts.
Is the conversion accurate?
Yes. It uses precise conversion factors and full numeric precision, so results are exact rather than rounded estimates.
Is this tool free?
Yes — free, instant, and unlimited, with no signup.