How to calculate your electricity bill

How to calculate electricity cost by appliance

To get an accurate picture of your home's energy consumption, you’ll need 3 figures to calculate the electricity usage of each appliance or electronic device: 

• The wattage of the appliance
  
• The average number of hours you use it per day
  
• The price you pay per kilowatt-hour (kWh) of electricity

Your kWh rate is printed right on your electric bill, and you can estimate your average daily use. To determine the wattage of an appliance, look for a label or metal plate, which is usually in an hidden place like the back or bottom of the appliance or device.

If the wattage is listed, it will have a “W” at the end. If you can’t find a label, check the appliance’s original documentation or try searching online for its technical specs.

Once you have your data, calculate the cost of use with this formula:

1. Multiply the device’s wattage by the number of hours the appliance is used per day
   
2. Divide by 1000
   
3. Multiply by your kWh rate

For example, if you have a 150-watt television that you watch 5 hours per day, it consumes 750 watt-hours per day (150 x 5 = 750). You'd then divide 750 by 1000 to convert 750 watt-hours into .75 kWh (750 ÷ 1000 = .75). If your electricity rate is 12¢ per kWh, that means it costs 9¢ per day to use your television (.75 x .12 = .09). That should account for about $2.70 of your monthly electric bill (.09 x 30 = 2.7).

It will take a lot of number crunching to do this with all the appliances, electronics, and lights in your home, so if you’re looking for an easier way, turn to technology.

Electricity bill calculation formula

Calculating a bill estimate requires some key information on your usage and plan rate, then you just apply this simple formula:

(Monthly usage × energy rate) + taxes & fees = estimated bill

Common household appliances and their average energy consumption

To calculate your electricity costs it's essential to know how your devices and appliances use electricity. This can also be helpful when trying to reduce usage. Here's a look at the typical energy consumption of some popular electronic devices:

• Video game systems: Your gaming console can be power-hungry. Newer models might use between 50 to over 200 watts. If you game a lot, this could add a fair amount to your annual electricity use – think 132 to over 225 kilowatt-hours (kWh) per year. 
• Smart TVs: These modern screens usually consume 50 to 200 watts when they're on, averaging around 100 watts. Even with all their smart features, their extra power use is generally quite small. 
• Laptops/computers: Laptops are generally efficient, typically using only 30-70 watts. Desktops, especially powerful gaming setups, will use more – anywhere from 70 to 500 watts. Knowing this can help you decide if it's time to power down. 
• Refrigerators: Your fridge runs constantly, so it's a significant energy user. When its compressor kicks in, it can draw 300-800 watts. Over a year, a typical modern fridge can consume 400-800 kWh, making it a key area for potential savings if it's an older model. 
• Electric ovens: Electric ovens use a lot of power, typically between 2,000-5,000 watts. Each hour of use can add 2-3 kWh to your bill, so plan your cooking wisely. 
• Microwaves: Quick meals are convenient, but your microwave uses a good chunk of power, usually 600-1,000 watts. Even short daily uses can add up to about 73 kWh per year. 
• Lights (LED): Switching to LED bulbs is a smart move as they're energy efficient, usually using only about 10 watts. If you leave a single LED light on for a couple of hours daily, it only adds about 7.3 kWh to your annual usage.

While these estimates can give you a general idea of how much energy your appliances consume, the actual amount will change based on their specific model, how old they are, how efficient they are and how you use them.