Estimate how much a heat pump costs to run in the UK from heat demand, SCOP and electricity price, then compare grants, maintenance and break-even against a gas boiler.
Running cost · Boiler Upgrade Scheme · SCOP sensitivity
Use your yearly gas use in kWh from a recent bill if you have it.
We convert the entered gas use to useful heat using boiler efficiency, divide by SCOP for heat-pump electricity, then add editable installation, grant, maintenance and one replacement within each 10, 15 and 20-year horizon.
Quotes, eligibility, system life, maintenance, future tariffs and future grant availability vary. This is an undiscounted cash-cost comparison, not financial advice; use installer heat-loss calculations and written quotes before deciding.
Take annual gas use, multiply by boiler efficiency to estimate useful heat, divide by the heat pump's SCOP, then multiply by electricity price. A home using 12,000 kWh of gas at 85% efficiency spends roughly £830 a year on heat-pump electricity at SCOP 3.2 and 26.11p/kWh.
Because a heat pump turns 1 unit of electricity into 3–4 units of heat, its running cost can rival a gas boiler even though electricity costs more per kWh than gas.
Searches for air source heat pump cost often mix upfront installation price with yearly running cost. This calculator keeps both visible and adds the Boiler Upgrade Scheme grant, maintenance and replacement timing.
The 10, 15 and 20-year totals are undiscounted cash costs. Change every assumption to match written quotes; future energy prices and replacement costs cannot be predicted.
SCOP (Seasonal Coefficient of Performance) is the average heat output per unit of electricity across the heating season. A SCOP of 3.2 means 3.2 kWh of heat per 1 kWh of electricity. Every 0.5 you add to SCOP cuts running cost by roughly 12–15%.
Bigger radiators, lower flow temperatures, and a well-sized system all raise SCOP. An undersized or rushed install can drag it down to 2.5, which is where heat pumps get an unfair “expensive” reputation.
A home currently using 12,000 kWh of gas at 85% boiler efficiency would spend roughly £830 a year running an air-source heat pump at 26.11p/kWh and SCOP 3.2. Your figure depends on heat demand, system design and tariff, so enter your own bill and quote figures.
Heat pump cost can mean either the upfront installation price or the ongoing running cost. This calculator shows both, then compares maintenance and replacement timing with a gas boiler over 10, 15 and 20 years. Finance interest is not included.
It depends on the price gap between electricity and gas. Because a heat pump delivers 3–4 units of heat per unit of electricity, while a gas boiler delivers less than one unit of heat per unit of gas, a heat pump can match or beat gas running costs even though electricity costs more per kWh. At a SCOP of 3.2, 26.11p electricity and 7.33p gas, a lower-cost tariff or higher SCOP can tip the comparison in the heat pump's favour.
SCOP (Seasonal Coefficient of Performance) is the average units of heat a heat pump produces per unit of electricity across a whole heating season. A SCOP of 3.2 means 3.2 kWh of heat for every 1 kWh of electricity. Higher is better and directly lowers your running cost. A well-designed system on radiators sized for low flow temperatures might reach 3.5–4.0, while an undersized or poorly installed system might only manage 2.5.
The easiest way is to look at your current annual gas use in kWh on a recent bill or your online energy account, and subtract a small amount for cooking if you cook with gas. The calculator can use that gas figure directly, or you can pick a home-size preset for a typical estimate (around 8,000 kWh for a flat up to 22,000 kWh for a large detached house).
Yes. Several UK suppliers offer heat-pump or time-of-use tariffs with a lower unit rate for part of the day. Running the heat pump more during cheaper periods can cut annual costs noticeably. Try entering a lower blended electricity price in the calculator to see the effect.
Yes. Enter both installation quotes and the grant that applies to you. The standard Boiler Upgrade Scheme grant for an eligible air-to-water heat pump in England and Wales is £7,500; some eligible off-gas-grid replacements rise to £9,000 from 21 July 2026. Eligibility and installer quotes must be confirmed separately.
