Power Converter
Convert between any two watt units in your browser — instant, accurate, and private.
Example
1 W = 0.001 kW. Switch the unit menus to convert between any pair.
How it works
Every value is converted through a single watt base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Power converters earn their keep wherever rated output has to be compared across industries that grew up speaking different languages. An electrician reads appliance nameplates in watts and kilowatts, a car or motorbike spec sheet quotes horsepower, a European manufacturer prints PS (metric horsepower), and an HVAC catalog rates furnaces and air conditioners in BTU/hour. Converting between them lets you size a generator against an air-conditioner load, compare a 150 hp engine to a 110 kW electric motor, or check whether a 1500 W space heater matches the 5,100 BTU/h figure on the box.
The split is really metric versus everything else. The watt is the SI unit, named after James Watt, and kilowatts and megawatts are just decimal steps (×1,000 each). Mechanical horsepower is the old imperial unit Watt himself coined, defined as exactly 550 foot-pounds per second, which works out to about 745.7 W. Metric horsepower (PS, CV, ch) was the continental European answer, defined as 75 kgf·m/s, landing slightly lower at about 735.5 W. BTU/hour comes from the thermal world, where 1 W equals roughly 3.412 BTU/h.
A few rules of thumb make these tractable in your head: 1 hp is roughly three-quarters of a kilowatt (multiply kW by 1.34 to get hp, or hp by 0.746 to get kW). To go from watts to BTU/h, multiply by about 3.41; a 1,000 W heater is therefore close to 3,412 BTU/h. And 1 kW is just shy of 1.36 metric horsepower.
The classic mistake is treating the two horsepowers as identical. Mechanical hp and metric hp differ by about 1.4 percent, so a "100 PS" European car is only about 98.6 mechanical hp — a gap that matters in marketing and motorsport. Also keep BTU/hour separate from plain BTU: the former is a rate of power, the latter a quantity of energy, and only the rate belongs on this page.
Frequently asked questions
What does the power converter do?
It converts between common watt units instantly. Pick a unit to convert from and a unit to convert to, type a value, and the result updates live.
Which units does this converter support?
It includes 6 units: Watt, Kilowatt, Megawatt, Horsepower, Metric horsepower, BTU/hour.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
How many watts are in 1 horsepower?
One mechanical (imperial) horsepower equals about 745.7 watts. Metric horsepower (PS) is slightly less, at about 735.5 watts.
What is the difference between mechanical horsepower and metric horsepower?
Mechanical horsepower is defined as 550 foot-pounds per second (~745.7 W), while metric horsepower (PS/CV) is 75 kgf·m/s (~735.5 W). Metric hp is about 1.4% smaller, so a 100 PS rating is roughly 98.6 mechanical hp.
How do I convert kilowatts to BTU per hour?
Multiply kilowatts by about 3,412 to get BTU/hour. For example, 2 kW is roughly 6,824 BTU/h.
How many BTU per hour is a 1500 watt heater?
A 1,500 W heater puts out about 5,118 BTU/hour, since 1 watt equals roughly 3.412 BTU/h.
How do you convert kW to hp quickly?
Multiply kilowatts by 1.341 to get mechanical horsepower, or by 1.36 for metric horsepower. So 100 kW is about 134 hp (or 136 PS).
What is a megawatt in horsepower?
One megawatt equals 1,000 kilowatts, which is about 1,341 mechanical horsepower (or roughly 1,360 metric horsepower).
Is BTU/hour the same as BTU?
No. BTU/hour is a unit of power (a rate of energy flow), while a plain BTU is a unit of energy. This converter handles BTU/hour, not BTU.
How many watts is 1 metric horsepower (PS)?
One metric horsepower equals about 735.5 watts, which is roughly 0.7355 kilowatts.
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