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Electricity Cost Calculator

Updated · By the CalculatorDash editorial team · How we check our maths

Quick answer

Running cost = watts ÷ 1,000 × hours × price per kWh. A 1,500 W space heater used 5 hours a day uses 7.5 kWh; at $0.17 per kWh that's about $1.28 a day, $39 a month and $465 a year.

Appliance running cost

watts
hours
days
$per kWh

Cost per year

$465

Cost per month
$38.78
Cost per day of use
$1.28
Energy per year
2,738

kWh

Cost per hour
$0.255

How this calculator works

Electricity is billed in kilowatt-hours (kWh): using 1,000 watts for one hour. To find what an appliance costs, convert its power to kilowatts, multiply by the hours it runs, and multiply by your rate per kWh from your bill.

Appliances with heating elements, such as space heaters, kettles, dryers and water heaters, draw the most power. Fridges and air conditioners cycle on and off, so their label wattage overstates real use; for those, the yearly kWh figure on the energy label is more accurate. Enter that by setting 1,000 W and the hours equal to the label's kWh ÷ days.

Rates vary a lot: averages are around 17 cents in the US, 25–30 pence in the UK and 30 euro cents in much of Europe, and time-of-use tariffs charge more at peak times. Use the rate on your own bill.

The formula

Energy per day
watts ÷ 1,000 × hours × number of appliances
Cost per year
kWh per day × price per kWh × days used

Worked example

1,500 W × 5 hours = 7.5 kWh a day. At $0.17 per kWh that's $1.28 a day. Over 365 days it's 2,738 kWh and about $465 a year, or $38.78 a month.

Tips

  1. 01A plug-in energy monitor shows the real consumption of any appliance in a day or two.
  2. 02Switching to LED bulbs uses about 80% less electricity than incandescent bulbs.
  3. 03Heat pumps and heat-pump dryers use a fraction of the energy of resistance heaters.

Frequently asked questions

How do I calculate electricity cost?

Multiply watts by hours used, divide by 1,000 to get kWh, then multiply by your price per kWh.

How much does it cost to run a 1,000 W appliance for an hour?

It uses 1 kWh, so it costs exactly your price per kWh, about 17 cents at the US average.

What uses the most electricity in a home?

Usually heating and cooling, water heating, then large appliances such as dryers, ovens and fridges.