Power Converter (Watts / kW / HP)
Convert power between watts, kilowatts, megawatts and both kinds of horsepower — mechanical (hp) and metric (PS). The kW-to-hp conversion every car spec sheet needs.
How to use this calculator
- Enter the power value.
- Choose the from and to units.
- Press Convert to see watts, kW, MW, hp and PS together.
Formula used
Mechanical horsepower (hp, 745.7 W) is the US/UK standard; metric horsepower (PS, 735.5 W) appears in European car specs. They differ by about 1.4% — small, but enough to matter in marketing.
Example calculation
A 100 kW car engine: 100 × 1.341 = 134.1 hp, or 136.0 PS. In reverse, a classic 300 hp engine is 223.7 kW.
Watts and horsepower
Power is energy per unit time — one watt is one joule per second. James Watt coined "horsepower" to sell steam engines against actual horses, defining it as 550 foot-pounds per second (745.7 W). Europe later rounded to a metric version (PS, 735.5 W), which is why the same car shows different horsepower on each side of the Atlantic.
Anchors: a human sustains ~100 W (Tour de France pros ~400 W), a kettle draws ~2 kW, a family car makes 70–150 kW, and a wind turbine 2–15 MW.
Why use this calculator?
- Convert car engine specs between kW, hp and PS correctly.
- Size appliances, solar panels and generators across unit conventions.
- Both horsepower definitions handled — most converters silently pick one.
Frequently asked questions
How many hp is 100 kW?
134.1 mechanical hp, or 136.0 metric PS. Rule of thumb: kW × 1.34 = hp; hp × 0.746 = kW.
What's the difference between hp and PS?
Mechanical hp = 745.7 W; metric PS = 735.5 W. PS values run ~1.4% higher for the same engine, which is why European brochures often quote PS.
How is power different from energy?
Power (watts) is the rate; energy (joules, kWh) is the total. A 2 kW heater running 3 hours uses 6 kWh of energy — power × time.