How to Figure Electricity Usage From Amps

Power comes in at 120 volts.

The amperage that comes into an appliance describes the amount of electricity running through it, but "electricity usage" usually refers to a different quantity. The device's electricity usage is the amount of energy it consumes, while the amperage is the rate of charge that flows into it. To figure electricity usage from amperage, you need to factor in the appliance's voltage, which describes the amount of energy in each unit of charge.

Instructions

1. Multiply the appliance's amperage by its voltage. If an appliance using 15 amps, for instance, takes in 120 volts, then 15 --- 120 = 1,800. This is its power consumption, measured in watts.

2. Multiply the device's power by the amount of time it runs. If it runs for 1,000 seconds, then 1,800 x 1,000 = 1,800,000. This is its energy consumption, measured in joules.

3. Divide this answer by 3,600,000, which is the number of joules in a kilowatt-hour, the most common unit of electric usage: 1,800,000 ÷ 3,600,000 = 0.5. The appliance uses 0.5 kWh of electricity.

References

• Georgia State University: Electric Power
• Boston University: Current and Resistance

Resources

• University of Oregon: How Much Energy Is a Kilowatt Hour?
• University of Wisconsin: What Is Energy?