Energy stored in a capacitor is equal to: 1/2 * c * v^2 Where c is the capacitance in farads, and v is the voltage. That will produce a value of joules. Note

Energy stored in a capacitor is equal to: 1/2 * c * v^2 Where c is the capacitance in farads, and v is the voltage. That will produce a value of joules. Note that the capacitor is rated for a given voltage, so that goes in as v. Converting watt hours to joules goes like this: A watt is one joule per second, so a watt hour is 3600 joules.