Understanding HP to kW Conversion

Horsepower (HP) and Kilowatts (kW) are the two most common units used to measure power in engines, motors, and industrial machinery. While HP is widely used in the automotive industry in the US and UK, kW is the standard unit in the International System of Units (SI) and is used globally for electrical and mechanical power ratings.

How to Convert HP to kW

The conversion factor depends on the specific definition of horsepower being used. Our calculator supports the three most common types:

• Mechanical Horsepower: Primarily used in the automotive industry. 1 HP ≈ 0.7457 kW.
• Metric Horsepower: Also known as PS (Pferdestärke) or CV. 1 HP ≈ 0.7355 kW.
• Electrical Horsepower: Used specifically for electric motors. 1 HP = 0.746 kW.

The Mathematical Formula

To convert manually, you can use the following standard formula:

P(kW) = P(hp) × Conversion Factor

For example, to convert 50 mechanical HP to kW: 50 × 0.745699 = 37.285 kW.

Frequently Asked Questions

Is 1 HP always equal to 0.746 kW?

Not exactly. While 0.746 is a common rounded figure for electrical HP, mechanical HP is slightly lower (0.7457), and metric HP is even lower (0.7355). It is important to know which standard your machinery follows.

Why is kW preferred over HP in modern specs?

Kilowatts are part of the metric system, making calculations for energy consumption and torque easier to integrate with other scientific units. Most modern electric vehicle manufacturers are now listing power in kW as the primary unit.