How we calculate

Both tools read one data file. The checker maps your answers to a published grant row. The estimator subtracts that grant from a published cost range.

Key takeaways

No hidden scoring.
Coal is not given the oil amount.
Cost ranges are air-to-water only.

Eligibility checker

Scotland and Northern Ireland stop first. Tenants stop next. A requested hybrid stops as not eligible. A new build returns “check first” with no amount, because most new builds are excluded and some self-builds are not. Everyone else in England or Wales gets a category.

Air-to-air is always £2,500. Air-to-water or ground source is £9,000 only for oil or LPG, and £7,500 for gas, electric and coal. Flats add a warning and do not change the amount. The end date of the uplift is 31 March 2027 from the data file.

Net cost estimator

The before-grant band is £10,000 to £16,000. The low and high ends bracket Energy Saving Trust’s typical £12,000 and the £13,431 average Which? reports for scheme installations in October to December 2025. We subtract the grant for the fuel and heat pump you pick. We do not produce a bedroom-by-bedroom price.

Ground source and air-to-air return the grant only. Running costs are omitted until tariffs are sourced. VAT is omitted.

Limits

The tools do not know if you are on a heat network, if a gas meter is still on the wall, or if the installer is certified. Those checks are why the result tells you the installer applies and Ofgem decides.

When the data file changes, we re-check the checker against the values notice before we move the last-checked date.

Sources

Reviewed by

Edward Thomson

MCIBSEHeat pump retrofits since 2005

UK Heat Pump & Funding Specialist

MCIBSE and MCS certified retrofit specialist. Director of Thomson and Sons Low Carbon Consulting Firm Ltd, specialising in heat pump retrofits since 2005.

Figures updated: 19 October 2026Content reviewed: October 2026Independent. Not affiliated with GOV.UK, Ofgem, MCS or any installer.