SmartCost Lab

Home Appliance Running Cost Calculator

Work out what any appliance costs to run per hour, day, month and year from its wattage or its energy per cycle — including the standby power it uses when you think it's off.

Last reviewed 16 October 2026 · How we build and check calculators

W

From the rating plate or manual. 1,500 W is only an example. For devices that cycle on and off, like fridges, a plug-in energy monitor gives a far better figure.

h
days
W

Many devices keep drawing a few watts when “off”. Measure it with a plug-in monitor, or leave blank to ignore.

¢/kWh

The price per kWh on your bill, including any taxes already built into it.

Reference rate: 18.31 ¢/kWh — U.S. average residential electricity price (average revenue per kWh, so fixed charges are already spread in; monthly, preliminary), U.S. EIA, Electric Power Monthly, Table 5.6.A, July 2026 (preliminary). Enter your own rate from your bill.

Running cost per year

$300.74

$25.06 per month · 1,643 kWh a year

Cost per hour running
$0.27
Per day (average)
$0.82
Per month
$25.06
Of which standby
$0.00

per year

Yearly cost at different daily hours (same days per week)
Show data table
1 h/day$100.25
2 h/day$200.49
4 h/day$400.99
8 h/day$801.98
12 h/day$1,203

Watts, kWh and why they're different

A watt is a rate — how fast a device uses energy at a given moment. A kilowatt-hour (kWh) is an amount: 1,000 watts for one hour. Your bill charges for kWh, so the calculator multiplies power by time:

kWh = watts × hours ÷ 1,000 cost = kWh × price per kWh

A 2,000 W heater running for 90 minutes uses 2,000 × 1.5 ÷ 1,000 = 3 kWh. At 30¢ per kWh that is 90¢.

Two ways to describe an appliance

By power works for things that draw a steady load while they're on: heaters, kettles, TVs, games consoles, lights, dehumidifiers. Find the watts on the rating plate, the charger, or the manual. By cycle is better for washing machines, dishwashers and tumble dryers, whose power swings up and down during a programme. Energy labels in the UK, EU and Australia, and ENERGY STAR data in North America, give kWh per cycle or per year for a standard programme.

The rating on a label is usually the maximum. Fridges, freezers, air conditioners and heaters with thermostats switch on and off, so their average draw is lower than the label. For those, the best figure is the annual kWh on the energy label or a reading from a plug-in energy monitor left in place for a few days.

Standby power

Many devices draw a small amount of power around the clock: set-top boxes, smart speakers, chargers, microwaves with clocks. The calculator applies your standby figure to every hour of the year the appliance isn't running. A few watts sounds trivial, but 5 W for 8,760 hours is 43.8 kWh a year — the same as running a 2 kW heater for almost 22 hours.

How the yearly figures are built

running hours per year = hours per day × days per week × 52.14 standby hours = 8,760 − running hours kWh per year = (watts × running hours + standby watts × standby hours) ÷ 1,000 per month = per year ÷ 12 · per day = per year ÷ 365

The bar chart shows how the yearly cost changes if you used the appliance more or less, so you can see whether cutting an hour a day is worth it. Use the scenario tabs to compare two appliances — for example an old and a new fridge, or a fan heater against an oil-filled radiator with the same output.

Common mistakes to avoid

  • Using the maximum wattage for a thermostat-controlled appliance — this can overstate the cost several times over.
  • Forgetting that a heater's cost depends on its power setting: a 2 kW heater on its 1 kW setting costs half as much per hour.
  • Comparing electric and gas appliances on kWh alone. For heating, use the Home Heating Cost calculator, which accounts for fuel prices and efficiency.

Sources

Results are estimates based on the figures you enter and the stated assumptions. They are not financial, tax, legal or engineering advice. Spotted a problem? Tell us.