Electric motor power is stated in watts. 750 watts = 1 horsepower.
An easy way to estimate power needs for RC hobby applications is to use 100 watts per pound for sport flying, 150 for aggressive aerobatics, 200 watts per pound for 3D flying.
The chart below also lists the roughly-comparable glow and gasoline power systems for reference.
Note that there are MANY more motors in the Hacker inventory than are listed below. Other motors can provide for different propeller, battery or performance profiles.
Glow Engine to Hacker Equivalent
Giant Scale / Gas Engine Equivalent