How we calculate appliance running costs
Price updated 9 July 2026 · Q3 2026 (Jul–Sep)
Every cost on this site comes from one short, transparent calculation. There is no hidden model and no magic — you can reproduce any figure with a calculator.
The formula
Electricity is billed per kilowatt-hour (kWh) — one kilowatt of power used for one hour. The two-step calculation is:
- Energy used (kWh) = watts × hours ÷ 1000
- Cost = kWh × price per kWh
For example, a 1,500W air fryer running for 30 minutes uses 1500 × 0.5 ÷ 1000 = 0.75 kWh. At 26.11p per kWh that is about 20p.
The electricity price we use
We use the Ofgem energy price cap unit rate for electricity, currently 26.11p per kWh (Q3 2026 (Jul–Sep)). This is the average capped rate for a typical direct-debit customer across England, Scotland and Wales, including VAT. It is the single value that drives every price on this site — when Ofgem changes the cap, we change one number and every page updates. You can always type your own unit rate into the calculator if your tariff differs.
How we treat days, weeks, months and years
A 'per day' figure is the cost on a day the appliance is actually used. Weekly, monthly and yearly figures are then built from how many days a week it is used, using 52.14 weeks a year so that the monthly figure multiplied by twelve equals the yearly figure exactly. This keeps the numbers internally consistent.
Where the wattages come from
Appliance power figures are typical published values compiled from public sources such as the Energy Saving Trust, manufacturer specifications and energy labels. Real appliances vary, so every appliance page shows a low–typical–high range rather than a single false-precision number. See our data and sources page for details.