The kilowatt (kW) equals 1,000 watts and is the standard unit for measuring the power output of engines, electric heaters, and industrial machinery. Electricity bills use kilowatt-hours (kW × hours), making the kilowatt the most familiar power unit for consumers. One kilowatt equals approximately 1.341 horsepower.

Calories per second (cal/s) equals exactly 4.184 watts, used primarily in thermodynamics and physics to express heat transfer rates. While not a common everyday unit, it bridges thermal and mechanical power calculations in scientific research. One calorie per second equals exactly 4.184 watts or about 0.00561 horsepower.