To calculate the wattage of a 5V 1A power supply, you can use the formula: Watts (W) = Volts (V) x Amps (A). In this case, 5V multiplied by 1A equals 5 watts. Therefore, a 5V 1A power supply provides 5 watts of power. This is a common power rating for many small electronic devices like phone chargers and USB-powered accessories.