Electricity Cost Calculator
Calculate daily, monthly and yearly electricity cost from watts, hours per day and electricity rate.
How to Use the Electricity Cost Calculator
Estimate the electricity cost of running any appliance based on its wattage, usage hours and your electricity rate.
- Enter power consumption — type the appliance wattage in watts (check the label or manual).
- Enter hours per day — how many hours the appliance runs each day (0 to 24).
- Enter number of days — the period you want to calculate for (default is 30 days).
- Enter electricity rate — your cost per kilowatt-hour in dollars (check your electricity bill).
- Read the results — energy consumption in kWh and estimated costs for daily, monthly and yearly periods.
- Copy any result — click on any cost card to copy the value.
The formula is: kWh = Watts × Hours / 1000, then Cost = kWh × Rate. All calculations are local.
Frequently Asked Questions
How do I find the wattage of my appliance?
Check the label on the appliance (usually on the back or bottom), the user manual, or the manufacturer's website. Common examples: LED bulb 10W, laptop 50W, refrigerator 150W, space heater 1500W, air conditioner 1000-3500W.
What is a kilowatt-hour (kWh)?
A kWh is the energy consumed by a 1,000-watt appliance running for 1 hour. For example, a 100W bulb running for 10 hours uses 1 kWh. Your electricity bill charges per kWh.
What is the average electricity rate?
The US average residential rate is about $0.12-$0.16 per kWh, but rates vary widely by state and country. Check your electricity bill for your exact rate. Some plans have time-of-use pricing with different rates during peak and off-peak hours.
How much does it cost to run a space heater?
A typical 1,500W space heater running 8 hours per day at $0.12/kWh costs about $1.44/day, $43.20/month, or $525.60/year. You can enter these exact values into the calculator to see your cost.
Does standby power cost money?
Yes. Many electronics consume 1-10W in standby mode (vampire power). A device using 5W continuously at $0.12/kWh costs about $5.26/year. While small individually, standby power can account for 5-10% of household electricity use.
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