Power Unit Converter

A power converter for kW to hp and hp to kW, watts to horsepower, metric horsepower and BTU per hour — with the two horsepowers kept apart.

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Runs entirely in your browser. What you enter stays on your device — nothing is sent to a server. Verify it yourself

How many horsepower is 1 kW?

1 kW is 1.341 mechanical horsepower, or 1.360 metric horsepower (PS). The two horsepowers differ by about 1.4%, which is why a European spec sheet in PS shows a slightly bigger number than an American one in hp.

Cost: Free, no limits
Upload: None — runs on your device
Sign-up: Not required
Works offline: Yes, once loaded

How to convert kW to hp

Enter the value
Type the number into the Value box; the result updates as you type.
Choose the units
Pick From and To — kilowatts and horsepower to begin with, or watts, metric horsepower (PS), BTU per hour or kilocalories per hour. The swap button between them flips the direction.
Read every unit at once
The All units table below the result shows the value in every power unit.

Examples

100 kW134.1 hp · 136 PS
The same engine in both horsepowers.
12,000 BTU/h3.52 kW
A "one-ton" air conditioner’s cooling capacity.

Key features of the Power Unit Converter

Converts between 9 power units
Converts as you type, in both directions
Metric and imperial in the same list
Runs entirely in your browser

Supported formats

Units

Watts
Kilowatts
Megawatts
Horsepower (mechanical)
Metric horsepower (PS)
BTU per hour
Tons of refrigeration
Kilocalories per hour
Foot-pounds per second

When should you use this?

Comparing car and motorbike power between kW, hp and PS.
Sizing a heater or air conditioner quoted in BTU per hour.
Converting motor and generator ratings.
Reading electrical loads in watts and kilowatts.

Limitations

Conversions go through a base unit, so a value converted from one unit to another and back can differ in the last decimal place. That is floating-point arithmetic, not a defect, and it is far below the precision of any real measurement.
Results are displayed rounded for readability. If you need a specific number of significant figures, round the displayed value yourself rather than assuming the display is exact.
Converting a measurement cannot make it more precise than it was. A length measured to the nearest centimetre is still that precise after conversion, however many decimal places appear.
Power ratings are not all measured the same way. A car’s figure may be at the crankshaft or at the wheels, and an air conditioner’s BTU/h is heat moved rather than electricity drawn. Converting the unit does not change what was measured.

Troubleshooting

The answer disagrees with another converter

Usually a different definition of the same unit name — US versus imperial, or a short versus a long ton. Check which variant each tool means before assuming one is wrong.

The last decimal place changes on a round trip

Conversion factors are not exact in binary floating point. The error is around one part in ten thousand billion, which no physical measurement can detect.

Common mistakes to avoid

Assuming a unit name is unambiguous. It very often is not.
Rounding partway through a multi-step calculation instead of at the end.
Treating PS and hp as the same unit. They are 1.4% apart — five horsepower on a 350 hp engine.

Pro tips

Tips for better results

US and UK units
The same unit name can mean two amounts
Check which system a unit belongs to before trusting it. Several unit names mean different amounts in the US and the UK.
Working method
Write the unit beside every number
Carry the unit through your working rather than converting at the end. Most unit errors happen when a number is written down without one.
Car figures
PS is already horsepower, just the metric kind
Check whether a European figure is PS or kW before converting: PS is already horsepower, just the metric kind.

Standards and terms behind the Power Unit Converter

The named things this tool works with, and the documents that define them.

SI unitsSpecification: The international system of units, maintained by the BIPM, which fixes the metre, kilogram, second and kelvin. Reference: SI units
Imperial and US customary unitsSpecification: Inches, feet, pounds, gallons and Fahrenheit — still standard in the United States and common in the UK.

Also searched as: kw to hp, horsepower conversion, watts to horsepower.

Two horsepowers

James Watt defined horsepower as 33,000 foot-pounds of work per minute — 745.7 watts. Continental Europe adopted a metric version, 75 kilogram-force metres per second, which is 735.5 watts and appears on spec sheets as PS, CV or pk. They differ by about 1.4%, so a 150 PS engine is 148 hp. American electric motors are sometimes rated in electrical horsepower, exactly 746 W — within a rounding of the mechanical figure.

Kilowatts on modern spec sheets

In the EU the kilowatt is the legal unit for engine power, so registration documents list kW and adverts add horsepower beside it. To convert, multiply kW by 1.341 for mechanical horsepower or by 1.360 for PS.

BTU per hour

Air conditioners and heaters in North America are rated in BTU per hour, often written simply as "BTU". A 12,000 BTU/h unit — a "one-ton" air conditioner — moves about 3.5 kW of heat. That is its cooling capacity, not the electricity it draws, which is typically a third of that figure or less.

Privacy

The Power Unit Converter runs entirely in your browser. What you enter and the result it produces stay on your own device — nothing is sent anywhere, because nothing needs to be.

You can confirm this rather than take our word for it: open your browser’s developer tools, watch the Network tab, and use the tool. No request carries your input. It also keeps working with the connection off.

Details are in the privacy policy.

What next?

For kWh, joules and BTU — the amount of energy rather than the rate.

Convert energy

Power Unit Converter — questions

How do I convert kW to hp?

Multiply by 1.341 for mechanical horsepower. A 100 kW motor is 134.1 hp — or 136 PS, if the figure you need is metric horsepower.

What is the difference between hp and PS?

hp is mechanical (imperial) horsepower, 745.7 W. PS is metric horsepower, 735.5 W. European manufacturers quote PS and American ones hp, so the same engine shows a slightly larger number in PS.

How many watts is a 12,000 BTU air conditioner?

About 3,517 W of cooling. The BTU figure is per hour and describes heat moved rather than electricity used; the electrical draw is usually around 1 to 1.5 kW.

Is a watt the same as a joule per second?

Yes, exactly. Power is energy per unit of time, so a 60 W bulb uses 60 joules every second — 0.06 kWh in an hour.

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