How to Calculate KWH Consumption

A lightbulb is rated for a certain number of watts, which can be used to calculate consumption.

Electricity is usually measured in kilowatt-hours (kWh), which is the number of kilowatts used in an hour's time. This figure is used to calculate your energy consumption and the amount billed by the electric company. You can calculate your own energy consumption by tallying the wattage requirements of your appliances and their average daily use. This figure would give you your daily usage, which could be extrapolated to monthly or annual usage.

Instructions

1. Look for the wattage rating of your devices. Some devices might list amps instead, which can be multiplied by voltage to calculate watts. As an example, a phone charger might be rated as 0.7 amps. You can multiply this number by the standard 110 volts to come up with a rating of 77 watts.

2. Estimate the average number of hours each device is used. As an example, if a 60-watt light bulb is kept on all the time, then you would multiply 60 watts by 24 hours to calculate 1,440 watt-hours.

3. Add all these watt-hours to tabulate your total watt-hours of usage. As an example, if you had watt-hours calculations of 1,440, 500, 560, 2,300 and 200; then your total watt-hours consumed would be 5,000 watt-hours.

4. Divide the number of watt-hours by 1,000 to calculate the number of kilowatt-hours used on a daily basis. In the example, this results in 5 kWh per day.

5. Multiply the daily usage by the number of days in the month to calculate monthly usage. In the example, 5 kWh times 31 days in January would yield 155 kWh per month.

6. Multiply the daily usage by 365 to calculate annual use. In the example, your annual usage would be 6,825 kWh.

References

• Orange & Rockland: Calculating Energy Use