Almost everyone gets their monthly electric bill and wonders how in the world they used that much electricity.
Instead of just turning to kilowatt-hour (kWh) calculators to get a guess, it’s good to know how to calculate your electric bill. A smart way to calculate is to figure out each appliance’s monthly electricity consumption. This way, you can see how much electricity each appliance is using per month, allowing you to realize where it is best to cut back and save.
Step 1: Figuring Watts Per Day
To calculate how much an appliance is costing you each month, first you need to figure out how many watts of electricity it uses per day. For example, most refrigerators use 300–780 watts, but let’s say you were one of the lucky ones who scored one that uses only 300 watts. To calculate how many watts your refrigerator uses per day, you would multiply the wattage (300) by the hours (24), to figure that you are using 7,200 watt-hours per day.
300 watts X 24 hours = 7,200 watt-hours per day
Step 2: Converting to Kilowatts
Next, you need to convert the 7,200 watt-hours per day to kilowatt hours per day (kWh per day) since monthly electricity bills measure in kilowatt hours (kWh). One kilowatt is equal to 1,000 watts, so to figure out the kWh per day that your refrigerator uses, you simply need to divide the watt-hours per day (7,200) by 1,000 for a total of 7.2 kWh per day.
7,200 watt-hours per day / 1,000 = 7.2 kWh per day
Step 3: Figuring Usage Over a Month
Now, you need to figure out how many kWh the refrigerator is using per month, not just per day. To do this calculation, you simply multiply the kWh per day (7.2) by 30 days to get 216 kWh per month.
7.2 kWh per day X 30 days = 216 kWh per month
Step 4: Figuring Overall Cost
Now you finally know your refrigerator is using 216 kWh per month and can figure out how much that is costing you per month. To calculate this cost, you will need to look at your latest monthly electric bill in order to see how much you are being charged per kWh. Let’s say that you pay 10 cents per kWh. To figure out how much the refrigerator is costing you per month, you multiply your kWh per month (216) by your electricity rate ($0.10) to get a grand total of $21.60 per month.
216 kWh per month X $0.10 per kWh = $21.60 per month1
Each one of your appliances should have a wattage label on it, allowing you to input that wattage number into this simple, four-step calculation. If you cannot find this label, the EPA has provided a list of typical wattage levels for your everyday devices.
Typical Wattage Levels:2
Coffeemaker: 900-1200 watts
Microwave: 750-1100 watts
Toaster: 800-1400 watts
Dishwasher: 1200-2400 watts
Washer: 350-500 watts
Dryer: 1800-5000 watts
Iron: 100-1800 watts
Ceiling Fan: 65-175 watts
Space Heater (40 gal): 4500-5500 watts
Hair Dryer: 1200-1875 watts
Laptop: 50 watts
Computer Monitor: 150 watts
Computer Tower: 120 watts
Television 19"-36": 65-133 watts
Television 53"-61": 170 watts
Now that you know all the necessary steps to figuring your appliances’ electricity consumption per month, it’s time to start calculating and saving!