Electricity Cost Calculator
Find what a single appliance costs to run per day, month, and year from its wattage and your electricity rate.
💡 What is the Electricity Cost Calculator?
The electricity cost calculator tells you what a single appliance costs to run. From its wattage, how long you use it, and your electricity rate, it works out the cost per day, per month, and per year, along with the energy used in kilowatt-hours. It answers the everyday question of what it really costs to leave that device on.
People use it to make decisions. Is it cheaper to run a space heater or turn up the central heating? How much is that old second fridge in the garage adding to the bill? Is a new energy-efficient model worth buying? By putting a number on each appliance, you can compare options, find the biggest drains, and decide where cutting back actually saves money rather than guessing.
The calculation rests on the kilowatt-hour, the unit your energy supplier bills. One kilowatt-hour is a thousand watts running for an hour, so a 1,000 watt appliance used for one hour costs exactly one unit at your rate. Dividing watts by 1,000 converts to kilowatts, multiplying by hours gives kilowatt-hours, and multiplying by the rate gives the cost. A frequent mistake is using an appliance's startup surge instead of its steady running wattage, which overstates the cost, so always use the running figure from the label.
This tool is useful because it turns a wattage label into real money over real time frames, and shows the working so you can see how hours of use and your rate drive the total. Compare a few appliances and the biggest opportunities to save jump straight out.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 - 1500 W space heater
Example 2 - 100 W light bulb
Example 3 - 2000 W air conditioner
❓ Frequently Asked Questions
🔗 Related Calculators
How do you calculate the cost to run an appliance?
Divide the power in watts by 1,000 to get kilowatts, multiply by the hours of use to get kilowatt-hours, then multiply by your electricity rate. A 1,500 watt heater run 4 hours a day uses 6 kWh, which at 0.15 per kWh costs 0.90 a day.
What is a kilowatt-hour?
A kilowatt-hour (kWh) is the energy used by a 1,000 watt appliance running for one hour, and it is the unit your electricity company bills. A 100 watt bulb left on for 10 hours also uses 1 kWh. Your rate is simply the price of one kWh.
How do I find the wattage of an appliance?
Check the label, nameplate, or manual, usually near the power cord or on the back. It may list watts directly, or volts and amps, in which case watts equals volts times amps. Use the running wattage, not the higher momentary startup surge, for cost estimates.
How much does it cost to run a 1500 watt heater?
At 0.15 per kWh, a 1,500 watt heater costs about 0.225 per hour (1.5 kW x 0.15). Run 4 hours a day that is 0.90 a day, about 27 a month, and roughly 328 a year. Heaters are among the most expensive appliances to run because of their high wattage.
How do I convert watts to kilowatts?
Divide watts by 1,000. So 1,500 watts is 1.5 kilowatts and 100 watts is 0.1 kilowatts. Electricity is priced per kilowatt-hour, so converting to kilowatts first makes the cost calculation straightforward.
Which appliances use the most electricity?
Anything that heats or cools: space heaters, air conditioners, electric water heaters, tumble dryers, ovens, and older refrigerators. Their high wattage, often combined with long running hours, makes them the biggest items on most bills. Lighting and electronics usually cost far less.
How do I calculate my monthly electricity cost for a device?
Find the daily kilowatt-hours (watts / 1000 x hours per day), multiply by the number of days in the month, then multiply by your rate. A 2,000 watt air conditioner run 6 hours a day for 30 days uses 360 kWh, which at 0.20 per kWh is 72 a month.
Does standby power cost money?
Yes, a little. Many devices draw 1 to 10 watts on standby to keep clocks, remotes, or network connections alive. One device is trivial, but across a whole home the phantom load can add several percent to a bill over a year. Switch off or unplug rarely used gear to save it.
Why is my estimate different from my actual bill?
Your bill combines every appliance plus fixed charges and taxes, while this calculator covers one device. Real usage hours vary, appliances cycle on and off, and tiered or time-of-use rates change the price per kWh. Use this to compare devices and estimate, not to reproduce the exact bill.