How to Calculate Kilowatt Hours

Step-by-Step Guide

1. 1

   Step 1: Find the wattage on the appliance label.

   Most high-power appliances have an energy label on the back or base of the appliance.
   
   Look here to find the wattage, listed as "W." This is usually the maximum power the device operates at, which may be much higher than the actual average wattage.The steps below will find a rough estimate of kWh from this number, but your actual kWh usage is usually lower.
   
   Some devices show a range of watts, such as "200–300W." It may be more accurate to choose the middle of this range, or 250W in this example. , Watts measure power, or energy used over time.
   
   Multiplying by a unit of time gives you an answer in terms of energy, which is what matters for your electrical bill.
   
   Example:
   A large window fan rated at 250 watts runs for an average of 5 hours a day.
   
   The fan's daily watt-hours equal (250 watts) x (5 hours / day) = 1250 watt-hours per day.
   
   For air conditioning and heating units, make separate calculations for each season.
   
   Refrigerators only draw power about ⅓ of the time, or about 8 hours a day if you never unplug them., A kilowatt is equivalent to 1,000 watts, so this step converts your answer from watt hours into kilowatt hours.
   
   Example:
   You've calculated that your fan uses 1250 watt hours of energy per day. (1250 watt hours / day) ÷ (1000 watts / 1 kilowatt) =
   1.25 kilowatt hours per day. , Now you know how many kilowatt-hours (kWh) the device uses every day.
   
   To calculate your kWH per month or per year, just multiply by the number of days in that period.
   
   Example:
   Over the course of a 30-day month, your fan would use (1.25 kWh / day) x (30 days / month) =
   37.5 kWh per month.
   
   Example:
   If you fan runs every day for a year, it would use (1.25 kWh / day) x (365 days / year) =
   456.25 kWh per year. , Your electricity bill lists the cost per kilowatt hour.
   
   Multiply this number by the kWh to find the amount you can expect to pay.
   
   Example:
   If energy costs 17 cents/kWh, running the fan will cost (0.17 dollars / kWh) x (456.25 kWh / year) = $77.56 per year (rounded to the nearest cent).
   
   Remember that estimates based on the listed wattage is a maximum.
   
   In reality you would be charged less than this.
   
   If you're looking at a different area than the one you live in, search online to find the cost of electricity.
   
   For US locations, start with the EIA website.
2. 2

   Step 2: Multiply wattage by hours used each day.

3. 3

   Step 3: Divide the result by 1

4. 4

   Step 4: Multiply your answer by the number of days you're measuring.

5. 5

   Step 5: Multiply by the cost of electricity per kWh.

Detailed Guide

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