Is a single appliance secretly destroying your electric bill? Use our free kWh calculator to track down the energy hogs in your house. Every power company in America bills you based on the kilowatt-hours (kWh) you consume. By converting the wattage label on your TV or space heater into a monthly kWh cost, this tool shows you exactly how much money each appliance burns.
Energy Consumed
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Daily Cost
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Monthly Cost
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How to Use This Kilowatt-Hour Calculator
Finding the exact operating cost of your appliances is easy. First, look at the back or bottom of the appliance to find its wattage rating. Enter that number into the watts field. If it only lists Volts and Amps, simply multiply them together (e.g., 120 Volts × 10 Amps = 1,200 Watts).
Next, estimate how many hours a day the appliance runs. Finally, pull up your most recent electric bill and find your energy rate (the national average is roughly $0.16 per kWh). Hit calculate, and the tool will convert those watts into a dollar amount you can actually understand.
The kWh Formula Explained
An electric company does not bill you for watts; they bill you for energy used over time. The math behind a kWh calculator starts by multiplying the appliance's wattage by the hours used. This gives you "Watt-hours" (Wh).
Because Watt-hours are usually a massive number, we divide it by 1,000 to get Kilowatt-hours (kWh). For example, running a 1,500-watt space heater for exactly one hour uses 1.5 kWh of energy. The calculator then multiplies that 1.5 kWh by your local electricity rate to find the exact financial cost.
kWh Calculator Example
Let's look at a common winter mistake. A homeowner buys a 1,500-watt electric space heater and leaves it running in their bedroom for 8 hours every night. They pay the national average rate of $0.16 per kWh.
Using our calculator, 1,500 watts multiplied by 8 hours equals 12,000 watt-hours a night (12 kWh). At $0.16 per kWh, that tiny heater costs $1.92 every single night. Over a 30-day month, that one space heater adds a massive $57.60 to their electric bill! Meanwhile, a modern 50-inch LED TV only uses about 60 watts and costs less than $1 a month to run.
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Tips for Lowering Your Electric Bill in 2026
Watch the heat: Anything that changes temperature is an energy hog. Air conditioners, water heaters, clothes dryers, ovens, and space heaters consume 80% of a home's electricity.
Kill the vampires: "Vampire energy" refers to appliances that pull power even when turned off (like a gaming console in standby mode). Unplug them or put them on a smart power strip.
LEDs are mandatory: If you still have old incandescent light bulbs in your house, throw them in the trash immediately. A 60W incandescent bulb can be replaced by a 9W LED bulb that produces the exact same amount of light, slashing the energy cost by 85%.
Check your fridge: The refrigerator runs 24/7. If the rubber seals on the door are cracked, cold air leaks out, forcing the compressor to run constantly and draining your wallet.
Frequently Asked Questions
What is a kWh (Kilowatt-Hour)?
A kilowatt-hour (kWh) is a measurement of energy use over time. Specifically, it is the amount of energy required to run a 1,000-watt appliance for exactly one hour.
How do you calculate kWh?
Multiply the appliance's wattage by the number of hours you use it, and then divide that number by 1,000 to convert from watt-hours to kilowatt-hours.
How many watts are in a kWh?
There are exactly 1,000 watts in one kilowatt (kW). Therefore, running 1,000 watts for one hour equals one kWh.
Why is my electric bill so high?
Your bill is likely high due to 'energy hogs' in your house. Things that generate heat or cold (AC units, space heaters, water heaters, and ovens) pull massive amounts of watts.
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Don't let rogue appliances drain your bank account. Scroll back up and calculate exactly how much money that space heater is costing you.