Electricity Cost Calculator
Estimate what a device costs to run each day, month, and year.
What this calculator does
This calculator estimates how much electricity a device uses and what that usage costs. It is useful for appliances, lights, chargers, space heaters, fans, and other devices with a known or estimated wattage.
Inputs and results
Device wattage is the power draw in watts. Hours used per day is the average daily runtime. Electricity price per kWh is the rate from your electric bill.
The results show estimated daily cost, monthly cost using 30 days, and yearly cost using 365 days. Energy use is based on kilowatt-hours: watts divided by 1,000, multiplied by hours used.
How the calculation works
The calculator converts watts to kilowatts, multiplies by daily hours, and then multiplies by your price per kWh. For example, a 100 watt device used 5 hours per day uses 0.5 kWh per day. At $0.15 per kWh, that costs about $0.08 per day.
Worked example
A 1,500 W space heater used for 3 hours per day uses 4.5 kWh daily. At $0.18 per kWh, that is about $0.81 per day, $24.30 per 30-day month, and $295.65 per year if used every day.
Tips for interpreting results
Actual costs can vary because many devices cycle on and off or use different power levels. Your bill may include delivery charges, tiered rates, taxes, or fees that are not captured by a single kWh price. For the best estimate, use measured wattage from a plug-in power meter.
Frequently asked questions
What is a kilowatt-hour?
A kilowatt-hour is 1,000 watts used for one hour. It is the unit most electric bills use for energy consumption.
Does this include utility fees?
No. It estimates energy cost from the kWh rate you enter. Fixed fees, taxes, and tiered pricing are not included.
Where do I find my price per kWh?
Look for the energy charge on your electric bill. If your bill has several charges, divide the energy portion by total kWh for an approximate rate.
Why might my real cost be different?
Devices may not draw their rated wattage constantly, and utility rates can vary by time, location, or usage tier.