Electricity Cost Calculator
Find out how much an appliance costs to run by entering its wattage, usage hours, and your electricity rate.
Example
A 100 W fan running 5 hours a day for 30 days uses 100 / 1000 x 5 x 30 = 15 kWh. At $0.15 per kWh that costs 15 x 0.15 = $2.25.
How it works
Energy in kilowatt-hours = power (W) / 1000 x hours per day x number of days. Cost = energy (kWh) x price per kWh. Daily and yearly figures are scaled from the same per-day energy use.
Good to know
The Electricity Cost Calculator turns four numbers — an appliance's wattage, how many hours a day you run it, how many days, and your electricity rate per kWh — into a clear running-cost estimate. It is handy for anyone trying to pin down which devices are quietly inflating their bill, from renters deciding whether a space heater is worth it to remote workers tallying up a desktop PC, monitors, and a portable AC over a month.
Reach for it before a purchase (comparing an old fridge against an energy-efficient model), when a bill jumps unexpectedly, or when you want to know the real cost of leaving something on standby all day. Because every field updates the result instantly, it doubles as a quick "what if" tool: bump the hours or the rate and watch the yearly figure move.
When reading the output, keep the distinction between the two kinds of numbers in mind. "Total cost" and "Energy used" reflect exactly the days you entered, while the Per day / Per month (30d) / Per year (365d) tiles project your single day's usage across a fixed calendar period — so they answer "what if I ran it like this every day" rather than summing your actual entry. The kWh figure is the one to compare directly against the usage line on your utility bill.
A practical caveat: nameplate wattage is usually the maximum draw, not the typical one. Motors, fridges, and anything that heats or cools cycle on and off, so their real average consumption is often well below the label. For appliances like these, a plug-in energy meter gives a far more accurate hours-and-watts picture than the rated figure, and remember to include per-unit taxes in your price so the estimate matches what you actually pay.
Frequently asked questions
Where do I find an appliance's wattage?
Check the label on the device or its power supply, usually shown as W (watts). If only volts and amps are listed, multiply them: watts = volts x amps. For appliances rated in kilowatts, multiply by 1000 to get watts.
How do I find my price per kWh?
Look at your electricity bill for the rate charged per kilowatt-hour (kWh). It is often listed under usage or energy charges. Enter that number, including any per-unit taxes, for the most accurate running-cost estimate.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Your inputs never leave your device, and it works offline once loaded.
Is this calculator free?
Yes, completely free with no sign-up and no limits.
People also ask
How much does it cost to run a 1500W heater for 8 hours a day?
At 1500W for 8 hours, that is 1.5 kW x 8 = 12 kWh per day. Multiply by your rate per kWh — for example, at $0.15/kWh it is about $1.80 per day, or roughly $54 over a 30-day month.
How do I convert watts to kilowatt-hours?
Divide watts by 1,000 to get kilowatts, then multiply by the number of hours the device runs. For example, 100 watts running for 5 hours is 100 / 1000 x 5 = 0.5 kWh.
Why is my actual electricity bill higher than this calculator's estimate?
Bills often include fixed daily supply or connection charges, taxes, and tiered or time-of-use rates that a single per-kWh figure does not capture. This tool estimates only the energy cost of the appliance you entered.
Does an appliance use electricity when it's turned off but plugged in?
Many devices draw a small amount of standby or 'phantom' power while plugged in, typically a few watts. You can estimate this cost by entering the standby wattage with 24 hours per day.
What is the average electricity rate per kWh?
Rates vary widely by country, region, and provider, and change over time. Check the energy or usage section of your own electricity bill for the exact rate that applies to you.
How can I lower the running cost of an appliance?
Running cost falls when you reduce wattage, hours of use, or your per-kWh rate. Common approaches include using lower-power or higher-efficiency models, cutting daily run time, and shifting use to cheaper off-peak hours where time-of-use pricing applies.
How do I calculate watts if my appliance only lists volts and amps?
Multiply volts by amps to get watts. For example, a device rated at 120 volts and 5 amps draws about 600 watts.
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