Horsepower to Kilowatts
Convert horsepower to kilowatts instantly. Free, fast, no signup.
How to use this tool
- Enter horsepower in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your kilowatts and the full breakdown beneath it.
Convert horsepower to kilowatts instantly. Free, fast, no signup.
Formula
Kilowatts = Horsepower × 0.745700
One mechanical horsepower is defined as exactly 550 foot-pounds of work per second. Converting to SI: 550 ft·lbf/s × 0.3048 m/ft × 4.44822 N/lbf ≈ 745.700 W = 0.745700 kW.
How it works
To convert mechanical horsepower to kilowatts, multiply by 0.745700. The mechanical horsepower is defined as 550 ft·lbf/s; converting foot-pounds per second to watts using SI definitions yields exactly 745.69987 W, which rounds to 0.7457 kW. This conversion is commonly used when comparing engine power ratings between vehicles from different markets (US horsepower vs. European kilowatts).
Common mistake: Using the metric horsepower (PS, Pferdestärke) factor of 0.7355 kW instead of the mechanical hp factor of 0.7457 kW. These two horsepower definitions differ by about 1.4%, which matters when reading European car specs versus US specs.
Worked example
Convert 1 horsepower to kilowatts
- Start with the input: 1 mechanical horsepower (hp).
- Apply the conversion factor: 1 × 0.745699872 = 0.745699872.
- Round to four decimal places: 0.7457 kW.
1 horsepower = 0.7457 kilowatts
Common mistakes to avoid
- Mixing up mechanical horsepower (745.7 W) with metric horsepower (PS, 735.5 W) or electrical horsepower (746 W exactly) — using the wrong type can skew motor sizing.
- Confusing kW (power) with kWh (energy): horsepower is a rate, not a total energy figure.
- Applying this converter to boiler horsepower (9,810 W), which is an entirely different unit used for steam output.
Key terms
- Horsepower (hp)
- A unit of power originally defined by James Watt. Mechanical (US) horsepower equals exactly 550 ft·lbf/s ≈ 745.7 W. Metric horsepower (PS) is slightly different at 735.5 W.
- Kilowatt (kW)
- An SI unit of power equal to 1,000 watts. Used internationally to rate engine and motor output.
- Watt (W)
- The SI base unit of power, defined as one joule of energy transferred per second. 1 kW = 1,000 W.
- Metric Horsepower (PS/CV)
- A European power unit defined as the power to lift 75 kg by 1 metre per second, equal to 735.499 W — slightly less than the US mechanical horsepower (745.700 W).
Frequently asked questions
- How do I convert horsepower to kilowatts?
- Multiply the number of horsepower by 0.7457 to get kilowatts.