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Free Heat Pump Calculators

Work out your BUS grant eligibility, running costs and estimated savings before committing to a heat pump installation.

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BUS Grant Eligibility Checker
Most popular
5 quick questions to find out if you qualify for the £7,500 Boiler Upgrade Scheme grant.
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£
Running Cost Calculator
Compare annual heat pump running costs against your current gas, oil or LPG heating. Includes Ofgem Q1 2026 tariffs.
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%
Savings Estimator
Estimated annual savings and payback period based on your property type, bedrooms and current heating.
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kW
Heat Pump Size Calculator
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Work out what kW heat pump you need. Based on property type, bedrooms, insulation level and build age.
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Which calculator should I use first?

Most homeowners start with the BUS grant eligibility checker, because whether you qualify for the £7,500 changes the maths on everything else. Next, run the running cost calculator to see how a heat pump compares to your current fuel bill. Then use the savings estimator for an indicative payback period with the grant applied, and finally the heat pump size calculator to sanity-check what kW rating an installer should be quoting for.

The data behind our calculators

  • Ofgem Q1 2026 price cap — electricity 24.5p/kWh, gas 6.4p/kWh, standing charges excluded.
  • UK heat-demand data — typical annual kWh by property type and bedroom count, weighted to the national average.
  • SCOP assumptions — 2.8 for poorly insulated homes, 3.2 average, 3.6 well insulated with low-flow design.
  • BUS grant value — £7,500 in England and Wales; Scotland uses the HES loan instead.

When to trust the numbers

These calculators are directional, not contractual. They give a realistic ballpark so you can decide whether to go further, but real savings depend on your installer’s heat-loss survey and how the system is commissioned. Before signing any contract, read our MCS installer guide, check whether your home is ready with is my home suitable?, and get quotes from MCS installers to compare against the calculator figures.

About these calculators: All calculations use Ofgem Q1 2026 tariffs (electricity: 24.5p/kWh, gas: 6.4p/kWh) and average UK heating demand data. Results are estimates only and should not be relied upon for financial decisions. Always commission a professional heat loss survey.