You can estimate the monthly cost of any appliance with three numbers: its power in watts, how many hours it runs, and your electricity rate. This guide shows the method and a worked example.
The formula
Monthly cost = (watts ÷ 1,000) × hours per day × 30 × rate per kWh
Your rate is usually shown in cents per kWh on your utility bill. Divide cents by 100 to get dollars before you multiply.
Worked example
A 60 W ceiling fan running 4 hours a day, at an average residential rate of about 16.5 cents per kWh:
- Daily energy = 0.06 kW × 4 hours = 0.24 kWh
- Monthly energy = 0.24 × 30 = 7.2 kWh
- Monthly cost = 7.2 × $0.165 ≈ $1.19
Typical wattages
Use your appliance's own label for an accurate figure. Typical values from manufacturer energy labels:
| Appliance | Typical power | Notes |
|---|---|---|
| Ceiling fan | about 20 to 70 W | Energy Guide labels for individual models show about 33 to 69 W. ENERGY STAR listings show much lower figures on low speed. |
| Refrigerator | varies | Use the EnergyGuide label's yearly kWh figure instead, because the compressor cycles on and off. |
Check your rate
Find your rate on your electricity bill. The US average residential price was about 16.5 cents per kWh in 2024, according to the U.S. Energy Information Administration (EIA). Your local rate may be higher or lower, and some utilities use tiered or time-of-use pricing. If yours does, use your average rate for the month.
Try it on the calculator
Enter your appliance's watts and hours in the Electricity Bill & Device CO₂ Calculator to compare monthly costs side by side.
Sources: EIA Electric Power Monthly, Table 5.6.A (residential average price, 2024). ENERGY STAR ceiling fan listings and EnergyGuide labels for ceiling fans. This is an educational estimate for an appliance running steadily.
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