Direct answer

This calculator compares annual heating cost on mains gas versus an air source heat pump, from your own gas use figure, boiler efficiency and heat pump SCOP. It uses Ofgem's price cap unit rates for 1 October – 31 December 2026 as defaults, which you can overwrite with your own tariff. It is an estimate, not a quote, and it excludes standing charges.

Work it out for your home
Change any figure and the result updates automatically.
Ofgem's typical value is 9,500 kWh — use your own bill if you have it.
Annual cost — gas
£757.15
Annual cost — heat pump
£708.45
Difference
−£48.70
The heat pump is cheaper to run at these figures.
Break-even SCOP at these prices
2.81
Above this SCOP, the heat pump is cheaper to run.
Useful heat9,500 kWh gas × 85% efficiency = 8,075 kWh useful heat
Gas cost9,500 kWh × 7.97p ÷ 100 = £757.15
Heat pump electricity8,075 kWh useful heat ÷ 3.0 SCOP = 2,692 kWh electricity
Heat pump cost2,692 kWh × 26.32p ÷ 100 = £708.45
Break-even SCOP85% × (26.32p ÷ 7.97p) = 2.81 SCOP
Based on Ofgem price cap rates for 1 October to 31 December 2026 (electricity 26.32p/kWh, gas 7.97p/kWh, GB Direct Debit average). There is no VAT on electricity until 31 March 2027, which flatters this comparison relative to a normal quarter. Your own tariff may differ, especially on a time-of-use or fixed tariff. This is an estimate, not a quote, and it excludes standing charges. (Ofgem price cap)

How the calculation works

Direct answer

We convert your gas use into useful heat using your boiler's efficiency, then divide that same useful heat by the heat pump's SCOP to get its electricity use — then price both at their own unit rate. The break-even SCOP is the point at which both cost the same at your entered prices: boiler efficiency × (electricity price ÷ gas price).

This mirrors how a heat pump and a boiler actually deliver heat: a boiler burns gas at some efficiency to produce useful heat, while a heat pump moves that same amount of useful heat using electricity, at an efficiency (SCOP) that is typically well above 100%. Because both routes are converted to the same useful-heat figure first, the comparison is fair regardless of which system you're costing.

Calculator FAQ

What is SCOP?

Direct answer

SCOP (Seasonal Coefficient of Performance) is the average number of units of heat a heat pump delivers for every unit of electricity it uses over a year. A SCOP of 3.0 means 3 kWh of heat for every 1 kWh of electricity. It depends on system design, flow temperature and your home's fabric, not on the brand — see our FAQ on running-cost complaints for why.

Why use my own gas bill instead of a typical figure?

Direct answer

A typical UK gas-use figure can be well off for your specific home, so your own annual gas kWh figure — from a recent bill or your online account — gives a far more accurate comparison. The default of 9,500 kWh is Ofgem's typical domestic consumption value, useful only as a starting point.

Does this include standing charges?

Direct answer

No — this calculator compares only the cost of the energy used to heat your home, not the daily standing charge you pay regardless of usage. Standing charges apply to both gas and electricity accounts and don't change based on which heating system you run, so they don't affect the comparison between the two.