Calculate Energy Cost For a Device
- Read the wattage on the label of the device
If the device doesn’t have a label, you can buy a wattage measuring device, such as the Kill A Watt.
- Calculate Watts Per Day
To calculate energy consumption costs, simply multiply the unit’s wattage by the number of hours you use it to find the number of watt-hours consumed each day. For example, let’s say you use a 125 watt television for three hours per day. By multiplying the wattage by the number of hours used per day, we find that you are using 375 watt-hours per day.125 watts X 3 hours = 375 watt-hours per day - Convert to Kilowatts
But electricity is measure in kilowatt hours on your electricity bill. Since we know that 1 kilowatt is equal to 1,000 watts, calculating how many kWh a particular device uses is as easy as dividing by 1,000.375 watt-hours per day / 1000 = 0.375 kWh per day - Calculate Usage Over a Month Period
Now to find out how much that’s actually going to cost you on your electric bill, you’ll have to take the equation a bit further. First you’ll need to figure out how many kWh the TV uses per month.375 watt-hours per day X 30 days = 11.25 kWh per month - Calculate Monthly Cost
Next, pull out your last electric bill and see how much you pay per kWh. For this example, let’s say you pay 10 cents per kilowatt hour. To find how much the TV is costing you in a month, multiply your electricity rate by the kWh per month that you calculated above.
11.25 kWh per month X $0.10 per kWh = $1.13 per month