Electricity Cost Calculator
Work out what an appliance or device costs to run per hour, day, month and year from its wattage, the hours you use it and your price per kWh
Last updated: November 9, 2026
How to Use the Electricity Cost Calculator
How to use the electricity cost calculator
- Pick an appliance or enter your own. The quick-start list fills in a typical wattage and daily use for common devices. For anything else, type the power from the label, in watts or kilowatts.
- Enter the hours of use per day. Be realistic, such as 5 hours for a television or 0.25 hours for a microwave.
- Set the number of devices if you have several of the same kind.
- Choose your currency and enter your price per kWh. Use the rate from your electricity bill. Each currency starts with a typical price you can replace.
- Adjust the full-power time if needed. Open the advanced options for devices that cycle on and off, like a fridge or air conditioner.
The results show the cost per day, month and year, the energy used, and a table that includes the cost for each hour the device is on.
This is an estimate of the energy charge only. Your bill may also include fixed fees, taxes and tiered or time-of-use rates, which can change the real cost.
How the Electricity Cost Calculator Works
How to calculate electricity cost
Electricity is billed in kilowatt-hours (kWh). One kWh is the energy used by a 1,000-watt device running for one hour. To find what a device costs, convert its power to kilowatts, multiply by the hours it runs, and multiply by your price per kWh:
Energy (kWh) = (Watts ÷ 1,000) × Hours used
Cost = Energy (kWh) × Price per kWh
Worked example
A 1,500 W space heater runs 6 hours a day, and electricity costs $0.17 per kWh.
- Energy per day: (1,500 ÷ 1,000) × 6 = 9 kWh
- Cost per day: 9 × $0.17 = $1.53
- Cost per month (about 30.4 days): 273.75 kWh × $0.17 = $46.54
- Cost per year: 3,285 kWh × $0.17 = $558.45
Devices that cycle on and off
Some appliances do not draw their full rated power all the time. A refrigerator compressor, for instance, runs about 40% of the day. Use the time-at-full-power setting for these:
A 150 W refrigerator running 24 hours at 40% uses 0.15 × 24 × 0.40 = 1.44 kWh a day, which costs about $7.45 a month at $0.17 per kWh.
Finding the watts of your device
Look for the wattage on the label or in the manual. If you only see volts and amps, Watts = Volts × Amps. A plug-in power meter measures the real use of any appliance, which is the most accurate way to check.
Finding your price per kWh
Your electricity bill lists the rate, either as a price per kWh or as cents or pence per kWh. If your bill has several rates or tiers, use the one that applies to the device you are testing, or divide the total charge by the total kWh for an average.
About Electricity Cost Calculator
Our electricity cost calculator is a free, easy-to-use tool designed to help youwork out what an appliance or device costs to run per hour, day, month and year from its wattage, the hours you use it and your price per kwh. For professionals or those who need quick calculations, our calculator provides accurate results instantly.
Frequently Asked Questions
How do I calculate how much electricity an appliance uses?
Divide its power in watts by 1,000 to get kilowatts, then multiply by the hours you use it. A 100 W television watched for 5 hours uses (100 ÷ 1,000) × 5 = 0.5 kWh. Multiply that by your price per kWh to get the cost.
What is a kilowatt-hour (kWh)?
A kilowatt-hour is the energy used by a 1,000-watt device running for one hour, and it is the unit your utility bills you in. A 100-watt bulb would need 10 hours to use one kWh.
How much does it cost to run a space heater or air conditioner?
A 1,500 W space heater running 6 hours a day costs about $1.53 a day at $0.17 per kWh, or roughly $46 a month. Air conditioners vary a lot by size and climate. Enter their rated watts and a realistic time at full power to estimate your own cost.
What is the average price of electricity?
It varies by country, state and utility. In the United States, residential electricity averages roughly 17 cents per kWh, while many parts of Europe pay 25 to 35 cents or more. Use the exact rate from your latest bill for the best result.
Why is my real bill different from the calculator?
The calculator estimates energy cost only. Bills also include fixed service charges, taxes, delivery fees, and sometimes tiered or peak-hour pricing. Appliances also use less than their label rating when they run at a lower setting or cycle off.
Which appliances use the most electricity?
Heating and cooling equipment, water heaters, clothes dryers and electric car chargers usually use the most, because they combine high wattage with long run times. Lighting, phone chargers and small electronics have a low cost per device, though standby use adds up across a home.
How can I lower my electricity cost?
Switch to LED bulbs, use efficient appliances, run heavy loads such as laundry off-peak if your plan offers cheaper hours, set the thermostat a few degrees closer to the outdoor temperature, and unplug devices that draw standby power. Use this calculator to compare the cost before and after a change.
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