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Check the appliance label or use values from the table below
US average: $0.12/kWh. Check your bill for actual rate.
Reference wattages for common household appliances:
| Appliance | Watts | Typical Hours/Day | Est. Monthly Cost* |
|---|---|---|---|
| LED Light Bulb (10W) | 10W | 5h | $0.18 |
| CFL Light Bulb (15W) | 15W | 5h | $0.27 |
| Incandescent Bulb (60W) | 60W | 5h | $1.08 |
| Laptop Computer | 50W | 8h | $1.44 |
| Desktop Computer | 200W | 8h | $5.76 |
| Gaming PC | 500W | 4h | $7.20 |
| TV (50" LED) | 100W | 4h | $1.44 |
| Refrigerator | 150W | 24h | $12.96 |
| Chest Freezer | 100W | 24h | $8.64 |
| Window AC (5,000 BTU) | 500W | 8h | $14.40 |
| Central AC (3 ton) | 3500W | 8h | $100.80 |
| Space Heater | 1500W | 6h | $32.40 |
| Electric Water Heater | 4500W | 3h | $48.60 |
| Washing Machine | 500W | 1h | $1.80 |
| Electric Dryer | 3000W | 1h | $10.80 |
| Dishwasher | 1800W | 1h | $6.48 |
| Microwave Oven | 1000W | 0.5h | $1.80 |
| Electric Oven | 2500W | 1h | $9.00 |
| Coffee Maker | 900W | 0.25h | $0.81 |
| Hair Dryer | 1800W | 0.25h | $1.62 |
| Vacuum Cleaner | 1200W | 0.5h | $2.16 |
| Ceiling Fan | 75W | 8h | $2.16 |
| Box Fan | 100W | 8h | $2.88 |
| Dehumidifier | 500W | 12h | $21.60 |
| Electric Vehicle Charger (Level 2) | 7200W | 4h | $103.68 |
* Estimated at $0.12/kWh national average rate.
An electricity cost calculation determines how much money you spend to operate an electrical appliance or device over a specific period. The fundamental formula is Cost = Power (kW) x Time (hours) x Electricity Rate ($/kWh). Utilities measure energy consumption in kilowatt-hours (kWh) -- one kWh equals 1,000 watts of power used for one hour. For example, a 100-watt light bulb running for 10 hours consumes 1 kWh. By multiplying the total kWh consumed by your utility rate (which varies by location, time of day, and usage tier), you can calculate the exact cost of running any appliance. This calculation is essential for budgeting household energy expenses, comparing the operating costs of different appliances, evaluating whether energy-efficient upgrades are worth the investment, and identifying the biggest contributors to your monthly electricity bill.
Check the nameplate label on the appliance for its wattage (W) rating. If only amps and volts are listed, multiply them together: Watts = Volts x Amps. For variable-speed devices like air conditioners, use the average wattage listed in the product specifications or the EnergyGuide label.
Determine how many hours per day the appliance runs. A refrigerator runs about 8 hours per day (its compressor cycles on and off), while a TV might run 4 hours. For intermittent devices like a microwave, estimate the total active time -- perhaps 15 minutes (0.25 hours) per day.
Convert watts to kilowatts by dividing by 1,000, then multiply by hours of use. For monthly consumption, multiply by 30 days. Example: A 1,500W space heater running 6 hours/day uses 1.5 kW x 6 h x 30 days = 270 kWh per month.
Find your rate on your utility bill (typically $0.10 to $0.30 per kWh in the US). Multiply: 270 kWh x $0.12/kWh = $32.40/month. For tiered rates, the cost per kWh increases as you use more electricity, so high-usage appliances push you into more expensive tiers.
Knowing the operating cost of each appliance lets you identify the biggest energy consumers in your home. Simple changes like switching from incandescent to LED bulbs can save $100+ annually. Running a space heater costs $30-50/month, making it cheaper to use a heat pump in many climates.
Before purchasing an energy-efficient appliance, calculate the annual savings to determine the payback period. A new ENERGY STAR refrigerator might save $50-80/year over a 15-year-old model. Knowing the exact savings helps you make informed purchasing decisions and justify the upfront cost.
Every kWh of electricity saved means less fuel burned at the power plant. The average US household emits about 7.5 tons of CO2 annually from electricity. By calculating costs and reducing consumption by 20%, you can save roughly 1.5 tons of CO2 per year while lowering your electricity bill by $200-400.
| State | Avg. Rate ($/kWh) | Monthly Bill (avg.) | Relative Cost |
|---|---|---|---|
| Hawaii | $0.33 | $168 | Very High |
| Connecticut | $0.25 | $150 | High |
| Massachusetts | $0.24 | $131 | High |
| California | $0.23 | $116 | High |
| New York | $0.20 | $112 | Above Average |
| New Jersey | $0.17 | $103 | Above Average |
| US Average | $0.16 | $137 | Average |
| Florida | $0.14 | $139 | Average |
| Texas | $0.13 | $137 | Average |
| Illinois | $0.13 | $95 | Average |
| Washington | $0.10 | $95 | Low |
| Louisiana | $0.10 | $120 | Low |
| Idaho | $0.09 | $92 | Very Low |
Rates are approximate residential averages based on EIA data. Actual rates vary by utility, plan, season, and usage tier.
Many utilities charge tiered rates where the price per kWh increases as your usage goes up. For example, the first 500 kWh might cost $0.10/kWh (baseline), the next 500 kWh costs $0.15/kWh, and anything above 1,000 kWh costs $0.25/kWh. High-usage appliances push you into the expensive tiers, making their true cost higher than a flat-rate calculation suggests.
TOU plans charge different rates depending on the time of day. Peak hours (typically 4-9 PM) may cost $0.30-0.50/kWh, while off-peak hours (late night to early morning) might be $0.08-0.12/kWh. Running large appliances like dishwashers and laundry during off-peak hours can significantly reduce your electricity bill.
Devices in standby mode (TVs, game consoles, chargers, microwaves with clocks) typically draw 1-10 watts each. The average US home has 20-40 such devices, consuming 200-400 kWh annually, costing $30-60/year. Using smart power strips or unplugging unused devices eliminates this waste.
Multiply the battery capacity (in kWh) by your electricity rate. For example, charging a 60 kWh battery from empty to full at $0.12/kWh costs about $7.20. Most daily charging is partial (20-30 kWh), costing $2.40-3.60. Level 2 chargers at 240V are more efficient than Level 1, losing less energy to heat during charging.
This varies by lease agreement. Some rentals include utilities in the rent, but most require tenants to pay separately. Even when included, understanding your electricity usage helps you be a responsible tenant and avoid excessive charges that might lead to billing adjustments or lease issues.
Compare the energy cost of different lighting technologies including LED, CFL, and incandescent bulbs to find the most economical option for your home.
Convert power in watts to energy consumption in kilowatt-hours over any time period. Useful for translating appliance wattage into utility billing units.
Convert kilowatts of power to kilowatt-hours of energy consumption. Ideal for calculating energy use of large appliances and industrial equipment.