kW to Horsepower Calculator & Conversion

This calculator converts power in kilowatts (kW) to mechanical horsepower (hp) instantly. Enter the power value in kilowatts, and you get the equivalent horsepower, along with the result in metric horsepower and electrical horsepower for comparison. The conversion uses the standard factor: 1 kW = 1.34102 hp (mechanical).

Formula

The conversion from kilowatts to horsepower is a simple multiplication:

hp = kW × 1.34102

Where:

• hp = mechanical horsepower (the common “hp” used for car engines, generators, and most machines)
• kW = power in kilowatts (the SI unit of power)
• 1.34102 = the conversion factor (exactly 1 hp = 0.745699872 kW, so 1 kW = 1/0.745699872 ≈ 1.34102 hp)

There are actually several different “horsepower” definitions. The calculator returns three common ones:

• Mechanical horsepower (hp) – used in the US and UK for engines, defined as 550 ft·lbf/s.
• Metric horsepower (PS or hp(M)) – used in Europe, defined as 75 kgf·m/s, equal to 0.73549875 kW.
• Electrical horsepower (hp(E)) – used for electric motors, defined as exactly 746 W.

Worked Example

Using the default value of 75 kW from the calculator:

1. Mechanical horsepower: 75 × 1.34102 = 100.58 hp
2. Metric horsepower: 75 × 1.35962 = 101.97 hp(M)
3. Electrical horsepower: 75 × 1.34048 = 100.54 hp(E)

So a 75 kW motor produces about 100.6 mechanical horsepower. Notice that metric and electrical horsepower are very close to mechanical, differing by less than 1.5%.

Why Are There Different Horsepower Definitions?

James Watt originally defined horsepower in the 18th century to compare steam engines with draft horses. He measured that a horse could lift 550 pounds one foot in one second, giving 550 ft·lbf/s. That became the mechanical horsepower.

When the metric system was adopted, European engineers created a slightly different unit based on kilograms and meters: 75 kgf·m/s, which equals 735.5 watts. That’s metric horsepower (PS – Pferdestärke, German for “horse strength”).

Electrical horsepower was defined later for electric motors as exactly 746 watts, which is close to but not identical to the mechanical value.

For most practical purposes, the difference is negligible. But when comparing specs from different countries, you should check which definition was used.

How to Convert kW to Horsepower Manually

If you don’t have a calculator handy, you can do it in your head with a good approximation:

• Multiply kW by 1.34 for mechanical hp (accurate to about 0.1%)
• Multiply kW by 1.36 for metric hp (accurate to about 0.03%)
• Divide kW by 0.746 for electrical hp (exact)

For example, 50 kW × 1.34 = 67 hp (exact: 67.05 hp). For reverse conversion, divide hp by 1.34102 to get kW.

Common Applications and Examples

Here are some typical power values and their conversions:

• Small electric motor: 1.5 kW ≈ 2.0 hp
• Compact car engine: 75 kW ≈ 100 hp
• Mid-size car engine: 150 kW ≈ 201 hp
• Large truck engine: 300 kW ≈ 402 hp
• Industrial generator: 500 kW ≈ 671 hp

When buying a car in Europe, you often see power in kW (or PS). In the US, it’s always in hp. This calculator helps you compare.

Common Mistakes and Pitfalls

The most frequent error is using the wrong conversion factor. Some people use 1.36 (metric) when they need mechanical hp, or they confuse kW with watts (1 kW = 1000 W). Always check which horsepower your source uses.

Another mistake is rounding too early. If you round 1.34102 to 1.34, you lose about 0.1% accuracy. For a 100 kW motor, that’s 0.1 hp – usually negligible, but for precise engineering, use the full factor.

Also, remember that this conversion is for power, not energy. A 100 hp engine doesn’t mean it uses 100 hp·h of fuel per hour; power is the rate of doing work.

Limitations of the Conversion

The conversion factor is exact and universal – it doesn’t depend on the type of machine. However, the rated power of an engine may differ from its actual output. For example:

• An electric motor’s nameplate rating is the mechanical output at the shaft, not the electrical input.
• An internal combustion engine’s rated horsepower is measured at the flywheel (brake horsepower) or at the wheels (wheel horsepower). Wheel horsepower is typically 10-15% lower due to drivetrain losses.
• In some countries, car manufacturers report power in PS (metric hp) but label it as “hp” – the difference is about 1.4%.

This calculator converts the numerical value; it cannot account for how the power was measured.

Frequently Asked Questions

Is 1 kW equal to 1.34 hp?

Yes, approximately. The exact conversion is 1 kW = 1.34102 mechanical horsepower. Many people round to 1.34 for quick mental math, which is accurate to about 0.1%.

How many kW is 1 hp?

One mechanical horsepower equals 0.745699872 kW. So to convert hp to kW, multiply by 0.7457. For example, 100 hp × 0.7457 = 74.57 kW.

What is the difference between kW and PS?

PS (Pferdestärke) is metric horsepower. 1 PS = 0.73549875 kW, while 1 mechanical hp = 0.7457 kW. So 1 PS is about 1.4% smaller than 1 hp. For a 100 kW engine, that’s 136 PS vs 134 hp.

Why do electric cars use kW instead of hp?

Electric motors are rated in kW because it’s the SI unit and it’s directly related to the electrical input (volts × amps). Also, kW gives a more accurate comparison because electric motors have near-constant torque, unlike gasoline engines. But many manufacturers still quote hp for marketing.

Does the conversion factor change for different fuels or engine types?

No. The conversion factor is a mathematical constant – it converts units of power, not the power itself. A 100 kW diesel engine and a 100 kW electric motor both produce 134 hp. The difference lies in how the power is delivered (torque curve), not in the unit conversion.

What is brake horsepower (bhp) and how does it relate to kW?

Brake horsepower is the power measured at the engine’s flywheel before losses in the gearbox, driveshaft, and wheels. It’s essentially the same as mechanical horsepower. So 1 bhp = 0.7457 kW. The term “brake” comes from the original method of measuring using a brake dynamometer.

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in kw | Power | kW | 75 | 0
out hp | Mechanical horsepower | hp | kw * 1.34102 | 2
out hp_metric | Metric horsepower | hp(M) | kw * 1.35962 | 2
out hp_electrical | Electrical horsepower | hp(E) | kw * 1.34048 | 2