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Power Converter

Power is a rate, not a total: watts, horsepower and BTU per hour all measure how fast energy moves, which is why a 75 kW motor, a 150 hp engine and a 12,000 BTU air conditioner can describe the same machine. Each scale grew up in a different trade — motoring, refrigeration, steam — so the numbers look unrelated. Enter any figure and the converter returns the rest at once.

Enter values

Read it off the appliance label, spec sheet or dyno chart

Kilowatts for appliances and cars, horsepower for engines

Results update as you type.

Results

In horsepower (hp)
134.1022
In watts (W)
100,000
In megawatts (MW)
0.1
In BTU per hour (BTU/h)
341,214.16
In foot-pounds per second (ft·lb/s)
73,756.21
Exact factor
1 kW = 1.341022 hp

How is the Power Converter calculated?

Type a value, choose the unit it is written in, and choose the unit you want back. The headline figure shows the answer in your target unit; the rows beneath repeat the same power in watts, kilowatts, horsepower and BTU per hour, so picking the wrong scale is obvious immediately. The last row prints the exact factor — 1 kW = 1.341022 hp — so you can repeat the sum by hand. Decimals are welcome, and values run from 0 up to a billion.

Formula

Everything passes through watts: watts = value × from-unit factor, then target = watts ÷ to-unit factor. Exact factors: 1 kW = 1,000 W · 1 MW = 1,000,000 W · 1 hp = 745.699872 W · 1 BTU/h = 0.29307107 W · 1 ft·lb/s = 1.355817948 W. Horsepower to kilowatts is × 0.745699872; kilowatts to horsepower is × 1.341022.

Example

A 75 kW electric motor is 75 × 1.341022 = 100.58 hp, which is why a 100 hp claim and a 75 kW claim sit on the same nameplate. Work backwards from a petrol engine rated 150 hp: 150 × 0.745699872 = 111.85 kW. An air conditioner listed at 12,000 BTU/h moves 12,000 × 0.29307107 = 3,516.85 W, or 3.52 kW, and one horsepower is about 2,544.43 BTU per hour. Torque fans may prefer foot-pounds per second: 1,000 W is 737.56 ft·lb/s.

Things to remember

The watt is the common denominator, so convert through it once and every rating on the page speaks the same language. Keep the exact factor — 1 hp = 745.699872 W, not a rounded 750 — and quote figures with the unit attached; 'about 100 horsepower' is honest, but '100.58 hp' is checkable.

Frequently Asked Questions

Which horsepower should I use — mechanical or metric?

Mechanical for most work: 1 hp = 745.699872 W exactly, the figure behind 550 ft·lb per second. Electrical horsepower is a rounded 746 W, and metric PS (Pferdestärke) is 735.49875 W, about 1.4% lower. Mixing them shifts a 150 hp engine by roughly 2 hp, so state which standard you used.

How do I convert kilowatts to horsepower quickly?

Multiply kilowatts by 1.341022. A 100 kW motor is 134.10 hp, and a 150 kW one is 201.15 hp. For the reverse, divide horsepower by 1.341022 or multiply by 0.745699872: a 100 hp engine is 74.57 kW. Round only at the end, because early rounding is visible on small motors.

Why do air conditioners use BTU per hour instead of watts?

BTU per hour describes heat moved rather than electricity consumed, which is how cooling capacity has always been quoted. 12,000 BTU/h — often called a ton of refrigeration after the ice it once replaced — is 3,516.85 W or 3.52 kW, so it compares directly with a heater's watt rating.

What does horsepower have to do with foot-pounds per second?

They are the same unit in different words: one mechanical horsepower is exactly 550 ft·lb per second, or 745.699872 W. A winch rated at 1,000 W delivers 737.56 ft·lb/s of shaft power. If a manual quotes torque and speed instead, multiply them: power equals torque times rotational speed.

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