Electricity Cost Calculator (per appliance)

Working out what a single appliance costs to run starts with one formula: kWh = (watts x hours used per day) / 1,000. Multiply the kWh figure by your unit rate and you have the daily cost. Under the Ofgem price cap for 1 October to 31 December 2026 the average electricity unit rate is 26.32p per kWh, with no VAT on electricity until 31 March 2027, plus a daily standing charge of 54.83p. That standing charge applies whatever you do, so it sits outside any per-appliance sum and belongs in the bill total rather than in the cost of one device.

Common household appliances vary dramatically in running costs. A tumble dryer (2,500W) costs about 66p per hour, an electric oven (2,000W) about 53p per hour, a washing machine (500W average) about 13p per cycle, while an LED light bulb (10W) costs just 0.26p per hour. Always check the wattage on the appliance's rating plate, since that figure is what the whole calculation rests on and it varies between models of the same kind.

Short bursts at high power often cost less than they look. A 3kW kettle boiling for 3 min comes to about 4p, and an electric shower at 9kW for 8 minutes costs around 32p. Low-wattage devices left on for hours behave the other way round. A 100W television across 4 hours is 11p, a 60W laptop over 8 hours is 13p, and an LED bulb at 10W for 4 hours is about 1p. An energy-efficient fridge-freezer, which never switches off, still accounts for only £40 to £70 a year, while a 3kW heat pump running 12 hours a day in winter reaches £9.48 a day.

Enter any appliance by wattage and usage pattern, and the daily, weekly, monthly and annual running costs appear together. Several devices can be lined up side by side to find the biggest consumers in your home and see where a more efficient model would repay itself fastest. Cap rates move, so treat the defaults as a starting point. The Ofgem unit rate has run at roughly 24 to 28p per kWh depending on the quarter, with an electricity standing charge of 50 to 65p a day, or £182 to £237 a year. Ofgem's typical household uses 2,500 kWh of electricity a year, about £658 at the October 2026 rate before the standing charge, and larger or all-electric homes use far more.

Fixed tariffs typically sit 1 to 3p per kWh below the price cap and buy longer-term certainty. With a smart meter and appliances you can schedule, time-of-use deals change the picture more sharply. Octopus Agile prices every half hour against the wholesale market, usually 10 to 25p per kWh and occasionally negative. Octopus Tracker sets a daily rate on the same basis, and Octopus Cosy, aimed at heat pumps, charges 12 to 15p at peak against 3 to 7p off-peak. The legacy Economy 7 arrangement gives cheap units between 11pm and 6am for storage heaters. Off-peak windows across these tariffs run 5 to 15p per kWh against 30 to 60p at peak, which is why overnight EV charging at 7 to 10p beats a daytime 30p.

Standing charges roughly doubled between 2020 and 2025, from an average 25p a day to 60p, and they apply whether you use anything or not. Critics argue that this penalises low users such as small households and pensioners, and gives no incentive to cut consumption. Ofgem has been reviewing the structure, and zero standing charge tariffs have appeared (Utilita, and an OVO trial in 2024), though the unit rate rises to compensate. They suit holiday homes and genuinely low-use households, and work against heavy users. Energy Helpline and the MoneySavingExpert Cheap Energy Club compare both shapes against your own consumption.

On the savings side, swapping a 60W incandescent for a 10W LED is worth £8 to £15 per bulb a year in heavy use, and A-rated appliances save £30 to £100 a year against D-rated ones over a 10 to 15 year life. A smart thermostat such as Nest or Hive takes £50 to £150 a year off heating, and the Energy Saving Trust puts standby draw at roughly 5 to 10% of a household bill. Insulation makes the largest difference, with 270mm of loft insulation and cavity wall work saving £200 to £500 a year. A 3.5kW solar system at £6 to £8k generates 3,000 to 3,500 kWh a year, worth £400 to £700 plus £80 to £200 in SEG export payments.