Electricity Cost Calculator
Calculate the energy usage (kWh) and monthly cost of running an electrical appliance.
Running this appliance 3 hrs/day quietly adds up to about $262.8 a year at your electricity rate.
- Daily Energy Use4.5 kWh
About the Electricity Cost Calculator
This calculator turns an appliance's power draw in watts, how many hours a day you run it, and your electricity rate into a concrete cost — daily, weekly, monthly and yearly. It's built for the moment you're wondering whether a space heater, an old fridge, or a gaming PC left on all day is actually costing you much.
People use it to compare running costs between two appliances, to spot which device is quietly driving up an electricity bill, or to decide whether upgrading to a more efficient model is worth it once the yearly savings are laid out in dollars.
The math is simple multiplication done locally in your browser — nothing about your appliances or your electricity rate is stored or sent anywhere.
How it’s calculated
Energy use in kilowatt-hours is watts multiplied by hours used, divided by 1000 (since a kilowatt is 1000 watts) — kWh is the unit utilities actually bill you on, not raw watts. That daily kWh figure is then multiplied by your cost per kWh to get a daily cost, which is projected out to weekly, monthly and yearly totals by simple multiplication.
Frequently asked questions
Where do I find an appliance's wattage?
Check the label on the appliance itself, its nameplate, or the manufacturer spec sheet — most list wattage directly. If only amps and voltage are given, multiply them together (watts = volts × amps) to get an estimate.
Where do I find my electricity rate?
Your utility bill lists a rate per kilowatt-hour, usually somewhere in the billing details or a rate summary section. Rates vary significantly by region and sometimes by time of day, so use your actual bill's number for the most accurate result.
Does this account for standby power when an appliance is off but plugged in?
No — this only calculates cost for the hours per day you specify as active use. Many electronics draw a small amount of standby power even when switched off, which this calculator doesn't separately account for unless you include it in your hours figure.
Why does a small wattage difference matter so much over a year?
Small daily costs compound — a device costing just a few cents a day can add up to tens of dollars over a full year of continuous use, which is exactly why the yearly figure is included alongside the daily one.
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