Your electricity bill shows the total, not which appliance is behind it. This calculator estimates the running cost of any single device, from a phone charger to a space heater or an electric car charger, so you can see what is worth unplugging, replacing or running at a different time.
How to use the electricity cost calculator
- Pick an appliance from the list of typical wattages, or choose Other and enter its watts or kilowatts.
- Enter the hours used per day and the days used per week.
- For appliances that cycle on and off, set the share of time it actually draws power (the duty cycle).
- Enter the number of units if you run several, such as light bulbs.
- Enter your electricity price per kWh from your bill, or keep the default of $0.17.
Electricity cost formula
Yearly energy multiplies the kWh per day of use by days per week and 52.14 weeks; monthly figures are the yearly total divided by 12.
Worked example
A 1,500-watt space heater runs 5 hours a day, every day, at 17 cents per kWh:
Energy: 1,500 ÷ 1,000 × 5 h = 7.5 kWh per day
Per year: 7.5 × 365 = 2,737.5 kWh × $0.17 = $465.38
Per month: 2,737.5 ÷ 12 = 228.1 kWh × $0.17 = $38.78. Each hour costs about 25.5 cents.
If the heater’s thermostat cycles it on 60% of the time once the room is warm, the cost falls to about $23 a month.
Typical appliance wattages
| Appliance | Typical watts | Cost per hour at $0.17 |
|---|---|---|
| LED bulb (60 W equivalent) | 9 | under 1 cent |
| Laptop | 50 | about 1 cent |
| TV, 55-inch LED | 100 | about 2 cents |
| Refrigerator (while running) | 150 | about 3 cents |
| Desktop computer and monitor | 200 | about 3 cents |
| Microwave | 1,100 | about 19 cents |
| Space heater or hair dryer | 1,500 | about 26 cents |
| Dishwasher with heated dry | 1,800 | about 31 cents |
| Electric clothes dryer | 3,000 | about 51 cents |
| Central air conditioner (3 ton) | 3,500 | about 60 cents |
| Electric water heater | 4,500 | about 77 cents |
| EV charger, Level 2 | 7,200 | about $1.22 |
These are typical figures; the label on your own appliance or a plug-in power meter gives a better number.
Where the savings are
Heating and cooling come first
Devices that make heat or cold, such as space heaters, air conditioners, water heaters, dryers and ovens, use the most power. Cutting their hours or their temperature setting saves far more than switching off small electronics.
Standby power adds up
Many devices draw a few watts even when off. A set of electronics drawing 10 watts around the clock uses about 88 kWh a year, roughly $15 at 17 cents. Smart power strips cut that to zero.
Time-of-use rates
If your utility charges more at peak times (often late afternoon and evening), running dishwashers, laundry and EV charging overnight can lower costs without using less energy. Enter your off-peak rate to compare.
Related calculators
Water heating is a large share of many bills; the water usage calculator shows where your household uses hot water. To check circuit loads, convert with the watts to amps calculator or the Ohm’s law calculator, and switch between kWh, BTU and joules with the energy converter.
Frequently asked questions
How do I calculate the cost to run an appliance?
Multiply the appliance's power in kilowatts by the hours it runs to get kilowatt-hours, then multiply by your price per kWh. A 1,500-watt heater running 4 hours uses 6 kWh, which costs $1.02 at 17 cents per kWh.
What is a kilowatt-hour?
A kilowatt-hour is the energy used by a 1,000-watt device running for one hour. Utilities bill by the kWh, so a 100-watt TV running 10 hours also uses 1 kWh.
What is the average electricity price in the US?
US residential electricity averaged roughly 17 cents per kWh in 2025, according to the US Energy Information Administration, but rates range from under 12 cents in some states to over 30 cents in others. Use the price from your own bill.
How do I find my appliance's wattage?
Look for a label or nameplate on the back or bottom of the appliance, or in the manual. If it lists amps and volts instead, multiply them: 10 amps at 120 volts is 1,200 watts. A plug-in power meter measures real use.
Why does my refrigerator cost less than its wattage suggests?
Refrigerators, freezers, air conditioners and thermostat-controlled heaters cycle on and off. A fridge compressor might run about a third of the time, so set the duty cycle to around 35% to reflect that.