Electricity Cost Calculator

Find how much an appliance costs to run per day, month and year from its wattage, hours of use and your electricity rate.

Check the label or manual; use the average draw for appliances that cycle on and off.

h/day
$ /kWh
Cost per month
$15.51
Running cost
$0$50$100$150$200Per day — Cost: $0.51Per dayPer month — Cost: $15.51Per monthPer year — Cost: $186.15Per year
Cost per day
$0.51
Cost per year
$186.15
Energy per day
3 kWh
Energy per year
1,095 kWh
Show the working
  1. Energy = 1 kW × 3 h × 1 = 3.000 kWh/day
  2. Cost = 3.000 kWh × $0.17 = $0.510/day
  3. Month = 365 ÷ 12 ≈ 30.42 days

Runs entirely in your browser. Nothing you enter is uploaded.

Formula

kWh per day = watts ÷ 1000 × hours per dayCost = kWh × price per kWhMonthly = daily × 365 ÷ 12

How it works

Your utility bills you for energy in kilowatt-hours (kWh): one kilowatt drawn for one hour. A 1,000 W space heater running for 3 hours uses 3 kWh; a 10 W LED bulb would need 100 hours to use one.

The US average residential rate is roughly 16–18 cents per kWh, but it ranges from around 11 cents to over 40 cents depending on the state and time of use. Divide the total on your bill by the kWh used to get your own all-in rate.

Appliances with thermostats or compressors — fridges, freezers, air conditioners, heaters on low — do not draw their rated power all the time. For those, use the yearly kWh from the EnergyGuide label, or measure with a plug-in power meter.

Frequently asked questions

How many watts is a kilowatt?

1 kW = 1,000 W. Horsepower ratings on motors convert at 1 hp ≈ 746 W.

What does standby power cost?

A device idling at 5 W around the clock uses 43.8 kWh a year — about $7.50 at 17¢/kWh. Several of them add up.

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