Find out what any appliance costs to run. Enter its power in watts, how many hours a day you use it, and the rate you actually pay per kilowatt-hour — the tool returns the energy it uses each day plus the cost per day, month and year. The preset (1,500 W for 3 hours a day at $0.15/kWh) draws 4.5 kWh a day and costs about $0.68 a day, or roughly $246 a year.
Results are estimates for planning and education, based on your inputs and standard engineering values (AWG resistance, NEC ampacity, resistivity). Electrical work can be dangerous and is governed by the NEC and your local code — verify all sizing with a licensed electrician and your authority having jurisdiction (AHJ). Not a substitute for professional design.
Calculator
Energy used per day
4.50 kWh/day
Cost per day
0.67 $/day
Cost per month
20.25 $/month
Cost per year
246.37 $/year
Formula
Energy per day in kilowatt-hours = watts ÷ 1,000 × hours per day. Cost per day = kWh per day × your rate ($/kWh). Monthly cost ≈ daily cost × 30 and yearly cost = daily cost × 365. The site stores no tariff: you supply the price you pay, so the result tracks your real bill and never goes out of date when energy prices change.
Worked example
A 1,500-watt space heater runs 3 hours a day. Energy = 1,500 ÷ 1,000 × 3 = 4.5 kWh per day. At a rate of $0.15 per kWh, that is 4.5 × 0.15 = $0.675 a day, about $20 a month and 4.5 × 365 × 0.15 ≈ $246 a year. Halve the run time or switch to a lower-wattage unit and the annual cost falls in direct proportion.
Frequently asked questions
How do I calculate the cost to run an appliance?
Take the appliance wattage, divide by 1,000 to get kilowatts, then multiply by the hours you run it to get kilowatt-hours (kWh). Multiply the kWh by the price you pay per kWh to get the cost. For a daily figure use hours per day; multiply by 30 for a month and 365 for a year. The only number you need to look up is your electricity rate, which is printed on your utility bill.
Where do I find the wattage of my appliance?
Check the nameplate or rating label, usually on the back, base or inside the door, or look in the manual. If it lists watts, use that directly. If it lists only volts and amps, multiply them: watts = volts × amps (for example 120 V × 5 A = 600 W). For motor-driven or heating appliances the running wattage is what matters for energy cost, not the brief startup surge.
What electricity rate should I enter?
Enter the all-in rate you actually pay per kilowatt-hour. Find it on your utility bill by dividing the total amount by the kWh used, which captures supply, delivery, taxes and fees together. US residential rates commonly fall somewhere around $0.10 to $0.35 per kWh depending on the state and plan. This calculator deliberately stores no rate of its own, so your own number keeps the result accurate over time.
Does standby or "vampire" power count?
Yes, and it adds up. Many devices keep drawing a few watts in standby — TVs, game consoles, chargers, microwaves with clocks. To include it, run the calculation a second time using the standby wattage and 24 hours a day, then add it to the active-use cost. A device idling at 5 watts around the clock uses about 44 kWh a year, which is small per item but real across a whole household.
Why are my monthly and yearly costs slightly different from 30 and 365 days?
This tool uses a flat 30-day month and a 365-day year for an even, comparable estimate. Real billing periods vary from 28 to 31 days, and a leap year has 366 days, so your actual bill will differ a little. Usage also rarely stays identical every day. Treat the monthly and yearly figures as planning estimates rather than to-the-penny predictions of a specific bill.
How can I lower an appliance’s running cost?
Three levers move the cost: wattage, run time and rate. Replace a high-wattage device with an efficient one (LED instead of incandescent, heat-pump instead of resistance heat), cut the hours of use or add a timer, and shift use to off-peak hours if you are on a time-of-use plan. Because cost is simply watts × hours × rate, reducing any one of the three lowers the total directly.
Source: kWh/day = watts ÷ 1,000 × hours; cost = kWh × the user-entered $/kWh rate (no tariff hardcoded). · All sources