How do you convert mA to watts?

To convert milliamperes (mA) to watts (W), you need to know the voltage (V) in volts that the current is operating at. The formula is: Watts (W) = Volts (V) × Amperes (A). Since 1 mA is equal to 0.001 A, you can convert mA to A and then use the formula: W = V × (mA/1000).