Electricity Cost Calculator
Use this electricity cost calculator to see what a space heater, window AC, TV or any other device costs to run. Enter its wattage, how many hours a day you use it and your price per kWh, or type in the monthly kWh from your bill. You get energy use and cost per day, month and year. The default rate is 18 cents per kWh, the 2026 U.S. residential average forecast by the EIA.
Updated
Results
- Cost per day
- Cost per year365 days by device, 12 months from a bill
- Energy per day
- Energy per month
- Energy per year
Results are estimates. See the methodology below.
How to use the calculator
- Choose By device to price one appliance, or From my bill to price a monthly kWh total.
- For a device, enter its power in watts (printed on the nameplate, power adapter or manual), the hours of use per day and how many identical devices you run.
- For a bill, enter the kWh used in the month, shown in the usage section of your statement.
- Replace the default price per kWh with your own rate. A quick way to get it: take the bill total, subtract the fixed monthly customer charge, and divide by the kWh billed.
If the label lists only amps, multiply amps by volts (120 V for most U.S. outlets) to get watts.
How the cost is calculated
Energy is power multiplied by time. A device drawing 1,000 watts for one hour uses 1 kilowatt-hour (kWh), the unit your utility bills you in:
kWh per day = watts × hours per day × number of devices ÷ 1,000
- Per month: kWh per day × 30 days.
- Per year: kWh per day × 365 days.
- Cost: kWh × your price per kWh.
In bill mode the calculator works the other way: daily use is the monthly kWh ÷ 30, and yearly use is the monthly kWh × 12.
About the default rate
The EIA's Short-Term Energy Outlook (October 2026) puts the average U.S. residential price at 18.2 cents per kWh for 2026, rounded here to $0.18. Your rate can be far from that: average retail prices in 2025 ranged from about 8 cents per kWh in North Dakota to almost 36 cents in Hawaii, and many utilities use tiered or time-of-use pricing.
Fixed charges are not included. The monthly customer or service charge you pay even at zero usage, plus any flat fees, stays on top of the result. The calculator shows the usage-based cost only.
Examples
1. Space heater, 1,500 W, 4 hours a day
The heater uses 6 kWh a day and 180 kWh a month. At $0.18 per kWh that is $1.08 a day and $32.40 a month. Run every day all year, it would use 2,190 kWh and cost $394.20.
2. Ten 9 W LED bulbs, 5 hours a day
Together they use 0.45 kWh a day and 13.5 kWh a month: $2.43 a month, or $29.56 a year for about 164 kWh.
3. A 900 kWh monthly bill
In bill mode, 900 kWh at $0.18 comes to $162.00 a month before fixed charges, about 30 kWh or $5.40 a day, and $1,944.00 over 12 months.
| Device | Watts × hours | kWh / month | Cost / month |
|---|---|---|---|
| Space heater | 1,500 × 4 | 180 | $32.40 |
| Window AC | 1,000 × 8 | 240 | $43.20 |
| 10 LED bulbs | 9 × 5 | 13.5 | $2.43 |
Reading the result
The wattage on a label is the maximum draw. Devices with a thermostat or compressor, such as refrigerators, AC units and space heaters on a low setting, switch on and off, so they often use less than the calculator shows for the same number of hours. For a refrigerator, the Department of Energy suggests counting about one third of the time it is plugged in. A plug-in watt meter gives the most accurate number.
Use the yearly figure to compare options, such as an old appliance against an efficient replacement or a space heater against your central heating.
Frequently asked questions
How do I calculate the cost of running an appliance?
Multiply its wattage by the hours you use it per day and divide by 1,000 to get kWh per day. Multiply by your price per kWh for the daily cost, then by 30 for a month or 365 for a year.
How much does it cost to run a space heater?
A typical 1,500 W heater on high uses 1.5 kWh per hour. At $0.18 per kWh, four hours a day costs $32.40 a month. On a lower setting or with its thermostat cycling, the real cost is lower.
What is a kilowatt-hour?
A kilowatt-hour is 1,000 watts used for one hour: a 100 W TV running for 10 hours, or a 2,000 W hair dryer for 30 minutes. Utilities bill electricity in kWh.
How do I find my price per kWh?
Your bill lists the rates for supply (generation) and delivery. Add the per-kWh charges together, or divide the bill total minus the fixed customer charge by the kWh used. If your utility uses tiers or time-of-use rates, use the rate for the hours the device actually runs.
Why is my bill higher than the calculator's result?
The calculator leaves out fixed monthly charges and flat fees, and it only counts the devices you enter. Heating, cooling and water heating usually make up much of a bill, and standby power from electronics adds up too.
Does a refrigerator run 24 hours a day?
It is plugged in around the clock, but the compressor cycles on and off. The Department of Energy suggests dividing the plugged-in hours by three to estimate running time, so enter about 8 hours a day at the rated wattage.
Sources
This is an estimate of usage-based cost only. Your actual bill depends on your utility's rate schedule, fixed charges, taxes and how much power each device really draws.