Energy Use Calculations

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Energy Calculation Formulas

If you do not live in the Fairbanks region but would like to calculate the power usage of an electronic device and its impact on your power bill, here is a step-by-step breakdown of the math involved.

First, determine the wattage the device uses.

Try one of these options:

  1. Measure the wattage used with a plug load analyzer which reads the wattage an electrical device uses. These are typically available at hardware stores or your local electrical utility provider.
  2. Read the labels on the device, wattage is commonly indicated on a majority of electronic devices.

Now for some math...

Step One: Convert watts to kilowatts.
Multiply the device wattage by 0.001, this gives you kilowatts.

W * (0.001) = kW

Step Two: Determine the cost of energy for one day's usage.
Multiply the kilowatts by the number of hours the device is powered on per day.
Multiply that number by the cost of energy from your local power utility.

(kW * Hrs) * cost of energy = daily cost of energy

Step Three: Use simple math to determine the cost per week/month/year.
Week: daily cost of energy * 7 days = weekly cost of energy to power device.
Month: daily cost of energy * 30 days = monthly cost of energy to power device.
Year: daily cost of energy * 365 days = yearly cost of energy to power device.


Optional: Analyze what percentage of your power bill this device is responsible for.

Step One: Determine the kilowatt hours the device uses per month.
Multiply kilowatts by the number of hours the device is powered on per day.
Multiply that number by 30 days.

(kW * Hrs) * 30 = monthly kilowatt hours

Step Two: Compare with your bill.
Take the monthly kilowatt hours you calculated and divide them by the KWH Used specified on your bill.

Monthly kilowatt hours / KWH used = percentage*

*multiply the percentage by 100 to show the actual percent number.

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