Quick, free energy calculators that do the sums for you, with the current UK price-cap figures built in. Nothing is saved and nothing is sent; it all runs in your browser.
Watts to kWh
Turn an appliance's wattage and run time into kilowatt-hours per day, month and year.
kWh to cost
Multiply kilowatt-hours by your unit rate to see what the energy actually costs.
kW to kWh
Convert a power rating in kilowatts and a run time into kilowatt-hours used.
Energy bill estimator
Units, unit rate and standing charge worked into an estimated bill for any period.
Energy price cap
Estimate your annual and monthly bill from your usage at the current cap rates.
Thermostat savings
What turning the heating thermostat down a degree or two saves over a year.
Amps to watts
Work out power in watts from a current in amps at UK mains voltage.
Watts to amps
Find the current an appliance draws, handy for fuses and extension leads.
EV charging cost
What it costs to charge an electric car at home, per charge and per mile.
Solar payback
How many years a solar PV system takes to pay for itself from the savings.
Heat pump cost
Compare the yearly running cost of a heat pump against a gas boiler.
Gas vs electric heating
What the same warmth costs from a gas boiler against a direct electric heater.
Storage heater cost
Running cost of a storage heater on an Economy 7 night rate.
Solar output
How much electricity a solar system generates a year, and its value.
Home battery savings
What a battery saves from the peak to off-peak rate gap, and its payback.
Petrol cost per mile
Fuel cost per mile and per year from your mpg and the pump price.
Electricity CO2
Turn kilowatt-hours into carbon emissions, with relatable comparisons.
Electric shower cost
Cost per shower, week and year from the shower's power and your habits.
Cost to boil a kettle
What each boil costs and what it adds up to over a year.
Immersion heater cost
Running cost of heating water with an electric immersion element.
Tumble dryer cost
Cost per load and per year, with the heat-pump-dryer saving.
Wh to Ah
Convert watt-hours to amp-hours for batteries at any voltage.
kWh to therms
Convert gas energy between kilowatt-hours and therms.
Appliance running cost
Cost per use, per day and per year for any single appliance.