A direct relationship exists between voltage, wattage and electrical current, or amps. Through this relationship, you can calculate the amount of amps used or required by a particular device. In the United States, the standard household voltage is 120 volts, although some appliances, such as hot water heaters or clothes dryers, may run at 240 volts. Armed with this knowledge, you need only know the wattage to calculate the amps.
Instructions
-
-
1
Look at the device's power plug. If it uses a standard household outlet, the voltage is 120 volts. If it plugs into a large, oddly shaped receptacle, then it's likely to use 240 volts.
-
2
Reference the device's wattage, which should be printed in the device's specifications or manual.
-
-
3
Divide the wattage by the voltage to calculate the number of amps. As an example, an 1,100-watt microwave would use 9.17 amps, because 1,100 divided by 120 equals 9.17.