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Electricity cost calculator: what an appliance costs to run

From an appliance's wattage and how long you use it, work out its energy use in kWh per day, month and year, and what it adds to your electric bill.

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Cost per year

$73.44

Noticeable Worth keeping an eye on in your energy budget.

Average cost per month

$6.12

Cost per day of use
$0.612
Energy use per year
432.0 kWh
Energy use per day of use
3.60 kWh
Cost of one hour at full power
$0.255

Yearly cost by hours of use

Energy use per yearAverage cost per monthCost per year
1 h/day current108.0$1.53$18.36
2 h/day current216.0$3.06$36.72
4 h/day current432.0$6.12$73.44
8 h/day current864.0$12.24$146.88
12 h/day current1,296.0$18.36$220.32
24 h/day current2,592.0$36.72$440.64

Find out what each appliance really costs

Your electric bill shows one total, not which appliance is behind it. This calculator estimates an appliance’s energy use in kilowatt-hours (kWh) and its cost per day, month and year from its wattage, how long you use it and your price per kWh. Use it to decide whether to replace an old space heater, compare dryers or see what a gaming PC left on all day really costs.

The formulas

  • kWh per day = watts ÷ 1,000 × hours of use × duty cycle × number of appliances.
  • kWh per year = kWh per day × days of use.
  • Cost = kWh × price per kWh.

The duty cycle accounts for appliances that switch on and off: a thermostat-controlled heater, an air conditioner or a refrigerator does not draw full power all the time.

Worked example: a 1,500 W space heater

Used 4 hours a day for 120 days a year, cycling on 60% of the time, at $0.17 per kWh.

  1. Energy per day: 1,500 ÷ 1,000 × 4 × 0.60 = 3.6 kWh.
  2. Cost per day: 3.6 × 0.17 ≈ $0.61.
  3. Energy per year: 3.6 × 120 = 432 kWh.
  4. Cost per year: 432 × 0.17 ≈ $73.44, or about $6.12 a month on average.

By hours of use (same heater)

Hours per day kWh per year Average monthly cost Cost per year
1 h 108 kWh $1.53 $18.36
2 h 216 kWh $3.06 $36.72
4 h 432 kWh $6.12 $73.44
8 h 864 kWh $12.24 $146.88
12 h 1,296 kWh $18.36 $220.32
24 h 2,592 kWh $36.72 $440.64

Typical appliance figures

Appliance Typical power Typical yearly use
Modern refrigerator 100–200 W when running 350–600 kWh
Electric clothes dryer 2,000–5,000 W 600–900 kWh
Central AC (3 ton) 3,000–3,500 W 1,500–3,000 kWh, climate dependent
Desktop PC (4 h a day) 150–300 W 200–450 kWh
Wi-Fi router, always on 6–15 W 50–130 kWh
LED bulb (4 h a day) 9 W 13 kWh

Ways to cut usage

  • Heating and cooling: setting the thermostat back 7–10 °F for 8 hours a day can save up to 10% a year on heating and cooling, according to the US Department of Energy.
  • Standby power: a switched power strip for the TV, console and speakers stops phantom loads.
  • ENERGY STAR and EnergyGuide labels: compare the estimated yearly kWh, not just the purchase price.
  • Time-of-use plans: run the dishwasher, laundry and EV charging off-peak if your utility offers lower night rates.

Your price per kWh depends on your utility, plan and season, and some bills add delivery charges per kWh. Divide your bill’s total energy charges by the kWh used for an all-in rate. Fixed monthly customer charges are not included here.

Frequently asked questions

How do I calculate an appliance's electricity use?

Energy (kWh) = watts ÷ 1,000 × hours of use. A 1,500 W space heater running flat out for 4 hours uses 6 kWh. If its thermostat cycles it on 60% of the time, it uses about 3.6 kWh.

How do I turn kWh into dollars?

Multiply the kWh by the price per kWh on your bill. At $0.17, 3.6 kWh costs about $0.61. Over 120 days of use, that is 432 kWh and roughly $73 a year for one heater.

Where do I find an appliance's wattage?

Look at the rating label, usually on the back or bottom, or in the manual. If only amps are listed, multiply amps by volts (120 V for most US outlets, 230 V in the UK and Europe). A plug-in watt meter measures actual use, including standby.

Which appliances cost the most to run?

Heating and cooling are usually the biggest loads, followed by electric water heaters, clothes dryers, ovens and electric vehicle charging. Refrigerators run all year, so even a modest wattage adds up. Devices on standby can add $50 or more a year in a typical home.

What is the UK price per kWh?

In Great Britain, Ofgem's price cap sets the maximum unit rate and standing charge for default tariffs and is updated every quarter; in 2025 the electricity unit rate was around 25 to 27 pence per kWh. Enter your own rate from your bill, and the result will be in the same currency even though the symbol shows dollars.

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Results are estimates provided for information purposes. They do not replace professional advice.

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