How many watts is 20 amps good for?

Could you please clarify the context in which you're asking this question? Watts and amps are related but not interchangeable units of measurement. Watts represent power, while amps represent electric current. The relationship between the two depends on the voltage of the circuit. Could you specify the voltage you're working with, so I can provide a more accurate answer to your question? Additionally, it's important to note that the maximum wattage a circuit can handle is determined by the wiring and components used, not just the amperage.