Appliance Running Cost Calculator (Standby Included)

Defaults last checked: October 29, 2026. Results are estimates.

Every appliance’s running cost comes from the same small formula: power × time × price. The only tricky part is standby, the few watts many devices draw all day while “off.” It’s small per device, but it adds up across a house and it runs 24 hours a day. This calculator includes it.

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How to use it

  1. Choose your country. We fill in the average household electricity price from the EIA (US), Ofgem’s price cap (UK), Victoria’s default offer (Australia), Hydro-Québec’s Toronto figure (Canada) or Eurostat (eurozone). Replace it with the rate on your bill for a more accurate answer.
  2. Enter the power when on, in watts. It’s on the rating plate or power adapter. For a better number, measure it with a plug-in energy meter.
  3. Enter hours of use per day and, if you know it, standby watts for the rest of the day.
  4. Adjust days per year for seasonal things like heaters, fans or dehumidifiers.

The formula

  • Energy per year (kWh) = (watts × hours on + standby watts × (24 − hours on)) × days ÷ 1,000
  • Cost per year = energy per year × price per kWh
  • Cost per hour of use = watts ÷ 1,000 × price per kWh

Worked examples

A 1,500 W space heater in the US, 4 hours a day for 120 days, at the EIA’s August 2026 average of 18.16 cents: 1,500 × 4 × 120 ÷ 1,000 = 720 kWh, so about $131 for the season, or 27 cents an hour.

A TV in the eurozone, 100 W for 5 hours a day plus 2 W standby, at Eurostat’s first-half 2026 euro-area average of €0.2851 per kWh: (100 × 5 + 2 × 19) × 365 ÷ 1,000 ≈ 196 kWh, so about €56 a year, of which standby is about €4.

10 W of always-on standby in the UK (a few chargers, a set-top box and a soundbar together), at Ofgem’s 26.32p cap rate: 10 × 24 × 365 ÷ 1,000 = 87.6 kWh, so about £23 a year for devices doing nothing.

Getting a better number

Rated watts are the maximum, not what most appliances draw on average:

  • Fridges and freezers cycle on and off. Use the yearly kWh on the energy label instead. Enter it as watts = kWh per year × 1,000 ÷ 8,760, with 24 hours a day.
  • Heaters, kettles and ovens have thermostats, so they often draw full power only part of the time.
  • Washing machines and dishwashers use most of their energy heating water, which varies a lot with the program.
  • Computers and TVs vary with what’s on screen.

A plug-in energy meter, left on for a day or a week, gives you the real figure, standby included. Our home energy monitor guide compares plug-in meters and whole-home monitors.

Compare supplier tariffs

Pick your region and the calculator ranks the tariffs we could verify on each supplier’s own price sheet or data feed, cheapest first for your yearly use. In the UK that is Octopus (Flexible and 12M Fixed), British Gas, EDF and E.ON Next across all 14 regions; in Australia, the standing offers of AGL, Origin Energy, EnergyAustralia and Red Energy in NSW, south-east Queensland, South Australia and Victoria. Each card shows the source and the date we last checked it. “Use this rate” copies that supplier’s unit rate into the calculator. In the Ausgrid area of NSW, all four standing offers come to about 33.14c/kWh and 166.19c/day including GST, because the Default Market Offer caps them. Market offers are usually cheaper, so treat the standing offer as the price to beat.

FAQ

How do I convert watts to kWh?

Multiply watts by hours, then divide by 1,000. A 2,000 W heater running for 3 hours uses 6 kWh.

Is it worth switching things off at the wall?

For devices with noticeable standby, often yes. Measure first: many modern devices draw well under 1 W on standby, but older set-top boxes and some audio equipment draw much more.

Why doesn’t my bill match the calculator?

Your bill includes a standing or daily supply charge and every appliance in the house. The calculator shows one appliance’s energy cost only.

Can I use it for an EV charger?

Yes, as a rough guide: enter the charger’s power and the hours it charges per day. Charging losses aren’t included. See our home EV charger buying guide for more on choosing one.

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