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Electricity Cost Calculator
What each appliance adds to your electric bill
With this electricity cost calculator you see what one appliance adds to your electric bill: a space heater, an air conditioner, an oven or a computer. You only need its wattage, hours of use and your rate.
The key idea
Wattage is not the cost: the cost is wattage times hours
A 1,500 W space heater running 4 hours a day uses 6 kWh: at an example rate of $0.17 per kWh, about $30.60 a month. A 9 W LED bulb on 5 hours a day uses 0.045 kWh a day: about 23 cents a month. To lower your bill, look first at high-wattage appliances you run for many hours.
How it is calculated
Energy use in kilowatt-hours (kWh) is the power in kilowatts times the hours of use:
kWh = Power (W) × Hours / 1,000
Cost = kWh × Rate per kWh
The wattage is on the appliance label or in its manual. Appliances with a thermostat (refrigerator, heater, air conditioner) do not run at full power all the time, so their real use is usually lower.
Your bill may also include a fixed monthly charge, delivery charges and taxes that do not depend on how much you use each appliance. Some plans charge different rates by time of day or by usage tier.
Worked example
A 1,500 W space heater running 4 hours a day: 1,500 × 4 / 1,000 = 6 kWh. At an example rate of $0.17 per kWh that is $1.02 a day and about $30.60 a month.
A 9 W LED bulb on 5 hours a day uses 0.045 kWh: about 23 cents a month at the same rate.
Typical cases
How much common appliances cost to run
The electricity cost of common appliances at $0.17 per kWh, with the hours a day shown. Your rate is on your bill.
| Appliance | Watts | Hours a day | Per month | Per year |
|---|---|---|---|---|
| Space heater | 1,500 W | 8 | $61.20 | $745 |
| Window air conditioner | 1,000 W | 8 | $40.80 | $496 |
| Electric oven | 2,400 W | 1 | $12.24 | $149 |
| Refrigerator | 40 W | 24 | $4.90 | $60 |
| TV | 120 W | 5 | $3.06 | $37 |
| Desktop computer | 200 W | 8 | $8.16 | $99 |
| Hair dryer | 1,800 W | 0.25 | $2.30 | $28 |
| LED bulb | 9 W | 5 | $0.23 | $3 |
Save or share this table as an image Common questions
Frequently asked questions
How do I calculate what an appliance costs to run?
Multiply its wattage by the hours of use and divide by 1,000 to get kWh. Then multiply those kWh by the rate per kWh on your electric bill to get dollars.
What is a kilowatt-hour?
It is 1,000 watts used for one hour. A 1,500 W heater uses 1.5 kWh in an hour, and a 100 W device takes 10 hours to use 1 kWh.
How much does a device on standby cost?
Very little each day, but it adds up over a year. A device that draws 5 W around the clock uses about 44 kWh a year: about $7.45 at an example rate of $0.17 per kWh. Check the label or a plug-in meter for the real draw.
Where do I find my rate per kWh?
On your electric bill or your utility's website. Rates vary by utility, state and plan, and some plans change the rate by time of day or by how much you use, so type in the one that applies to you.
How do I work out what my refrigerator uses?
Use the yearly energy use on its EnergyGuide label, in kWh per year, and multiply it by your rate per kWh. It is more reliable than the wattage, because the compressor turns on and off instead of running at full power all day.
Is the result what I will see on my bill?
No: it is only the cost of the energy that one appliance uses. Your bill also adds fixed charges you pay even if nothing is on, and taxes or fees that depend on your utility.
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