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Calculate appliance energy costs by wattage, usage hours, and electricity rate.
Electricity cost is the expense of running electrical devices, calculated by multiplying wattage by usage hours and your utility rate per kilowatt-hour (kWh).
| Appliance | Watts |
|---|---|
| Refrigerator | 150 |
| Window AC Unit | 1,200 |
| Central AC | 3,500 |
| Space Heater | 1,500 |
| Washing Machine | 500 |
| Dryer | 3,000 |
| Dishwasher | 1,800 |
| Microwave | 1,000 |
Formula
Monthly Cost = (Watts ÷ 1,000) × Hours/Day × Days/Month × Rate/kWhW = wattage of the appliance
H = hours of use per day
D = days used per month
R = electricity rate per kWh (from utility bill)
Worked Example
1,500W space heater, 6 hr/day, 30 days, $0.13/kWh
Did you know? The average U.S. household uses about 877 kWh per month, costing around $121 at the national average rate of $0.138/kWh.
Sources
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