How can I tell how much electricity I use each day?
Every appliance or electronic device you use is reflected in your monthly energy bill. But, some of those devices are costing you more than others. Do you know which ones? Below, we’ll tell you how to determine and control the energy hogs in your home; just follow these four easy steps:
1. Calculate the watts each device uses per day.
2. Convert watts to kilowatts. (1 watt = 0.001 kilowatts)
3. Determine the kilowatts an appliance uses per month.
4. Figure out the cost. (Some multiplication required.)
Why go through the effort? Because, by figuring out the biggest energy hogs in your home, you can adjust your usage – and lower your bill – by unplugging or simply using those devices less. Remember: Even small adjustments can help whittle down your energy expenses.
Calculating the energy cost of a specific device is fairly simple. You only need two numbers to get started: the device’s wattage and the number of hours you use it per day (this can be an estimate or you can keep a log).
How can I find the wattage of a device?
Most devices have a label listing how many watts they use. You can find this wattage label either on the device (usually on the bottom or back) or in the owner’s manual.
If you can’t find the wattage label, there are a couple other options to determine how much power the device uses.
1. Purchase a wattage measuring device, such as the Kill A Watt®, which displays the wattage of a device when you plug it in.
2. Contact the manufacturer with your device’s model number.
We’ve also provided a list that shows the common wattage of everyday household devices. Though the wattage of your particular device may vary, it should give you a rough estimate.
According to the Environmental Protection Agency, here are typical wattage levels of everyday devices:
|Coffee maker||900-1200 watts|
|Ceiling fan||65-175 watts|
|Space heater (40gal)||4500-5500 watts|
|Hair dryer||1200-1875 watts|
|Computer monitor||150 watts|
|Computer tower||120 watts|
|Television 19"-36"||65-133 watts|
|Television 53"-61"||170 watts|
How to calculate a device’s energy cost in 4 easy steps
Calculate Watts Per Day
In this step, simply multiply your device’s wattage by the number of hours you use it in a day. This will give you the number of watt-hours consumed each day. For example, say you use a 125-watt television for three hours per day. By multiplying the watts (125) by the hours used (3), we find that the television is consuming 375 watt-hours per day.
Convert Watt-Hours to Kilowatts
Electricity is measured in kilowatt-hours on your bill, not watt-hours. One kilowatt is equal to 1,000 watts, so to calculate how many kWh a device uses, divide the watt-hours from the previous step by 1,000. Using our previous example, this means you would divide 375 watt-hours by 1,000, resulting in 0.375 kWh.
Find Your Usage Over a Month
Now that you know the kWh used per day, multiply that by 30 to find your approximate usage for the month. So, if your daily usage is 0.375 kWh, your monthly usage would be 11.25 kWh.
Figure Out the Cost
For the final step, refer to your last electric bill to see how much you pay per kWh, i.e. your electric rate. Let’s say, according to your bill, your electric rate is 10 cents per kWh. Multiply your electric rate (0.10) by your monthly usage (11.25) to find out how much your TV is costing you in a month ($1.13).
What about devices that use more electricity?
In our last example, the TV’s energy cost was relatively inexpensive – but this isn’t the case for every device. Your refrigerator, for instance, runs 24 hours a day. Most refrigerators consume anywhere between 300 to 780 watts of electricity. Let’s say your model only uses 300 watts.
300 watts X 24 hours = 7,200 watt-hours per day
7,200 watt-hours per day / 1000 = 7.2 kWh per day
7.2 kWh per day X 30 days = 216 kWh per month
216 kWh per month x $0.10 per kWh = $21.60 per month
What are common wattages for household appliances
The wattages of appliances or other electronic devices can vary. Typically, older appliances use more energy while newer models are more efficient. ENERGY STAR appliances are among the most efficient.