Electricity Cost Calculator
Want to know what it really costs to run the tumble dryer, leave the gaming PC on overnight, or boil the kettle six times a day? Enter the appliance wattage, hours of use, and your unit rate in pence per kWh — easily found on your latest bill — to see the daily, weekly, and annual cost.
How is this calculated?
kWh used = (watts ÷ 1000) × hours. Cost = kWh × price per kWh. The Ofgem price cap sets a maximum default tariff that most UK households pay; in 2026 the unit rate sits broadly in the 22p–28p/kWh range with a daily standing charge on top. Fixed-rate tariffs and time-of-use tariffs (such as Economy 7 or EV-friendly tariffs) can be materially cheaper if your usage profile suits them. Standby loads are included if you set hours to 24.
Frequently Asked Questions
How do I find my current unit rate?
It's printed on every electricity bill, usually labelled 'unit rate' or 'p/kWh'. You can also see it in your supplier's app or online account. Rates differ between standard variable, fixed, and Economy 7 tariffs, and there's a separate daily standing charge that applies regardless of usage.
What's the price cap and how does it affect me?
Ofgem's price cap limits the unit rate and standing charge that suppliers can charge customers on a default tariff. It's reviewed quarterly and sets the ceiling, not a fixed price. If you're on a fixed tariff signed before the cap moved, you're paying that fixed rate not the cap.
Which appliances are the biggest culprits?
Anything that heats: electric showers (8–10kW for short bursts), tumble dryers (2–3kW for an hour), immersion heaters, electric heaters, and ovens. Always-on devices add up too — a desktop PC left running 24/7 at 100W costs around £230 a year at 26p/kWh.
Are smart meters worth getting?
They unlock time-of-use tariffs like Octopus Agile or EV tariffs that can be much cheaper if you can shift heavy loads to off-peak windows. The in-home display also makes invisible costs visible, which often nudges down household consumption by 5%–10% just through awareness.
Last updated: May 2026 · Rates sourced from HMRC