Energy tools
Free calculators that use the current Ofgem price cap (1 October to 31 December 2026) and live grid data. No sign-up, no tracking.
Electricity cost calculator
What an appliance or heater costs to run per hour, day, month and year at the current price cap rate.
OpenBest time to use electricity today
Live 48-hour forecast of the greenest hours on the GB grid, with the best window for your washing or car charging.
OpenEV charging cost calculator
What it costs to charge an electric car at home or on public chargers, per charge, per mile and per year, compared with petrol.
OpenSolar panel calculator
How much a home solar system would generate in your postcode area, what it saves at today’s prices, export income and payback.
OpenEPC rating running costs
What homes in each EPC band, A to G, really use in gas and electricity, and what that costs a month at today’s price cap.
OpenGas meter units to kWh
Turn a gas meter reading (m³ or ft³) or therms into kilowatt-hours and pounds, using the official UK formula.
OpenkW to kWh converter
Convert power (kW) and time into energy (kWh), or kWh back to kW, with worked examples.
OpenEnergy price cap tracker
Today’s Ofgem cap rates, the next announcement date and every cap since 2019 on one page.
OpenUK grid live
Where Great Britain’s electricity is coming from right now, and how much CO₂ each kWh carries.
OpenHow we build these tools
The calculators run in your browser and store nothing. Prices default to the Ofgem price cap averages for Great Britain, and you can type in your own tariff. Live tools read the National Energy System Operator’s Carbon Intensity API. Each tool shows its formula and sources; see our methodology for more. Results are estimates for general information, not financial advice.