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Electricity Cost Calculator
Use this free electricity cost calculator to find out what an appliance really costs to run, or what your whole home costs at your current rate. Enter the appliance's watts and how many hours a day it runs, or switch to monthly-usage mode and enter the kilowatt-hours from your bill. The calculator shows the daily, monthly, and yearly cost, plus the energy used, so you can compare appliances and see exactly where your electricity money goes.
Default $0.17 is the approximate US average residential rate. Change it to the rate on your own bill for a more accurate result.
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How it works
Electricity is billed in kilowatt-hours, usually shortened to kWh. One kilowatt-hour is the energy used by a 1,000-watt appliance running for one hour. Your bill multiplies the kilowatt-hours you used by your rate per kWh, so the whole calculation comes down to working out how many kilowatt-hours an appliance uses and then applying your rate.
In appliance mode, enter the appliance's power in watts, which you will find on its label or in its manual, and how many hours a day it runs. A 1,000-watt microwave running for one hour uses exactly 1 kWh. A 60-watt light bulb running for five hours uses 60 ÷ 1,000 × 5 = 0.3 kWh. Multiply the daily kilowatt-hours by the days per month to get the monthly total, then multiply by your rate to get the cost.
In monthly-usage mode, skip the appliance details and enter the total kilowatt-hours from your bill instead. The calculator divides that by 30 to estimate a daily figure and multiplies by 12 for the yearly figure. This mode is best when you want the cost of your whole home rather than one appliance, or when you already know your usage and only want to test a different rate.
The default rate of $0.17 per kWh is the approximate US average residential rate. Real rates vary a lot: some states charge under $0.12 per kWh while others charge over $0.30, and many utilities add time-of-use pricing, where electricity costs more in the late afternoon and evening. Always check the rate printed on your bill, including any delivery charges, for the most accurate result. The chart beside the calculator shows the monthly cost for each calendar month, using the real number of days in each month, which is why February is the shortest bar and the 31-day months are the tallest.
Small appliances add up faster than most people expect. A television, a game console, and a router left on standby draw power all day, and a space heater or a window air conditioner can cost more in a month than everything else in the house combined. Running the calculator once per appliance is the quickest way to find the expensive ones, and cutting an hour a day off a high-wattage appliance is usually worth more than unplugging a dozen phone chargers.
Worked example
A space heater rated at 1,500 watts runs for 6 hours a day, 30 days a month, and the electricity rate is $0.17 per kWh.
Step 1: Daily energy — 1,500 ÷ 1,000 × 6 = 1.5 × 6 = 9 kWh per day.
Step 2: Monthly energy — 9 × 30 = 270 kWh per month.
Step 3: Daily cost — 9 × $0.17 = $1.53 per day.
Step 4: Monthly cost — 270 × $0.17 = $45.90 per month.
Step 5: Yearly cost — $45.90 × 12 = $550.80 per year.
The space heater costs $45.90 per month, or $550.80 over a full year at that usage. Enter 1,500 watts, 6 hours, 30 days, and $0.17 in the calculator above and you will get exactly the same result. Cutting its use to 3 hours a day would cut the bill in half, to $22.95 a month.
FAQ
How much does it cost to run a 1,500-watt appliance for an hour?
At $0.17 per kWh, a 1,500-watt appliance uses 1.5 kWh in one hour, which costs 1.5 × $0.17 = $0.26 (about 26 cents). At a higher rate, such as $0.30 per kWh, the same hour costs $0.45.
What is a kilowatt-hour (kWh)?
A kilowatt-hour is a unit of energy: one kilowatt (1,000 watts) of power used for one hour. A 100-watt bulb running for 10 hours uses 1 kWh, and so does a 1,000-watt heater running for 1 hour. Electricity bills charge by the kWh.
What is the average electricity rate in the US?
The approximate US average residential rate is about $0.17 per kWh, which is the default in this calculator. Rates vary by state and by utility, so check your own bill — the rate is usually printed near the usage section, sometimes split into supply and delivery charges.
Why is my electricity bill higher in summer or winter?
Heating and cooling use far more power than lights and electronics. A window air conditioner or a space heater can draw 1,000 to 1,500 watts for hours at a time, so a hot or cold month can easily double your kilowatt-hours compared with a mild month.
How can I lower my electricity cost?
Start with the biggest users: heating, cooling, and water heating. Run high-wattage appliances fewer hours, use a programmable thermostat, switch to LED bulbs, and turn off standby power with a power strip. The calculator shows the dollar saving for each change before you make it.