UK Home Energy

Free home energy calculators

Free calculators to help you size up the savings, costs, and grants on heat pumps, solar, insulation, and more. No sign-up, no jargon.

Heat Pumps

Heat Pump Savings Calculator

Work out how much you could save each year by switching from gas, oil, LPG or electric heating to a heat pump. Uses the Ofgem price cap for 1 October to 31 December 2026 and the £7,500 government grant.

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Solar

Solar Panel ROI Calculator

Work out how much solar panels will save you and how long until they pay for themselves.

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Insulation

Insulation Savings Calculator

See how much each type of insulation could save you. 6 measures ranked with costs, savings, payback periods, DIY product links, and grant eligibility.

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Grants

Grant Eligibility Checker

Answer a few questions about your home and circumstances to see which energy grants you could claim.

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Heat Pumps

Heat Pump Size Calculator

Estimate your home's heat loss on the coldest design day and the heat pump size worth looking at, using the official EPC default values and the design temperatures MCS installers must use.

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EV

EV Charging Cost Calculator

What a year of driving costs on each way of charging an electric car, against a petrol car, using rates checked with each supplier and official source.

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Heat Pumps

Heat Pump vs Gas Boiler Running Cost Calculator

See the true total cost of ownership: heat pump vs gas boiler over 15 years. Includes tariff comparison, visual cost curve, and break-even analysis.

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Efficiency

EPC Calculator: What Each Upgrade Does to Your Rating

See which energy upgrades will improve your EPC rating the most. 11 measures ranked by SAP impact with costs, savings, grants, and product recommendations.

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More calculators inside our guides

Each of these sits in the guide that explains the answer, so you get the number and the reasoning together.

Heat pumps

Heat pump quote checkerIs your quote fair for its size? Checked against what households really paid.Heat pump noise checkerThe MCS 020 a) calculation: will it pass 37 dB at next door's window?Heat pump cost estimatorInstalled cost by home size, with the grant taken off.Boiler Upgrade Scheme calculatorWhat you'd pay after the £7,500 grant.Heat pump feasibility checkerIs your home ready for a heat pump, and what needs doing first?Radiator size checkerWill your radiators keep up at heat pump temperatures?Ground source cost calculatorGround source against air source, over the long run.Smart thermostat compatibilityWhich thermostats work with your heat pump.

Solar and batteries

How many solar panels do I need?For your usage, region and roof direction, from PVGIS.Free solar panels checkerEvery UK scheme that can fund solar, checked against its rules.Solar offer scam checkerHad a "free solar" offer? See how worried to be.Solar battery paybackThe honest maths on whether a battery pays for itself.Solar cost estimatorPrice a system, panels or tiles, with or without a battery.Solar plus heat pumpWhat solar is worth alongside a heat pump.Solar finance calculatorCash, loan or 0% finance compared.Does solar add value?What panels could do to your EPC and sale price.Solar in winterMonth by month output for your region.What can solar power?Which appliances your panels can actually run.Inverter recommenderString, hybrid or microinverters for your roof.Plug-in solar paybackIs a balcony kit worth it now it's legal?Portable solar outputWhat a portable panel makes, month by month.

EV charging

EV tariff rankerEvery EV tariff ranked for your household.Charge time and costHow long and how much to charge your car.EV charger grant checkerWhat's left and whether you qualify.Charge your EV from solarHow much of your driving your roof could cover.

Running costs at home

Electric heater running costPer hour and per winter, against gas.Dehumidifier running costWhat each model costs to run.Kettle running costWhat a cuppa really costs.Air conditioner BTU and running costWhat size you need and what it costs.Fan running costTower and pedestal fans compared.Power station runtimeHow long it'll run your kit.Air purifier cost of ownershipRunning cost plus filters.Hot tub running costWhat a hot tub really costs a year.Coffee machine cost per cupAgainst the cafe habit.Air fryer vs ovenWhich is cheaper for what you cook.Insulation cost estimatorEach measure priced for your house.Smart TRV system costHub, thermostat and valves, priced.