Convert power between watts, kilowatts, horsepower (metric) and BTU/h.
All units are converted via watts as a common denominator: the value is multiplied by the unit's watt factor, then divided by the target unit's watt factor.
Horsepower here is metric horsepower (PS/CV), defined as 75 kgf·m/s. It's very close to, but not exactly the same as, mechanical ("imperial") horsepower at 745.7 W, which is often used for engines in the US and UK.
A kilowatt (kW) is simply 1000 watts — the same unit, just a more practical order of magnitude for describing the power of, say, cars, heaters, or household electricity use.
Horsepower originated as a historical measure of how much work a horse could do, and different countries and industries eventually standardized slightly different precise definitions — including metric horsepower (PS/CV, 735.5 W) and mechanical horsepower (HP, 745.7 W).
BTU/h (British Thermal Units per hour) is a common unit for heating and cooling power in the US, often used for air conditioners, heat pumps and furnaces. The unit describes how much thermal energy is transferred or removed per hour.