How do you size a capacitor for a motor?

Multiply 0.5 times the square of the voltage. Call this result x. By continuing the example, you have 0.5 times 11.5 volts times 11.5 volts, or 66.1 square volts for x. Divide the need for starting energy, into joules, of the engine by x to reach the size of the necessary capacitor in the farads.