Gas Cost Calculator

Gas heating is the most common form of central heating in the UK, used by around 23 million households. The cost depends on your boiler efficiency, thermostat settings, insulation levels and the size of your home. The average gas unit rate is approximately 6.76p per kWh, with a daily standing charge of around 31.65p.

A modern condensing boiler operates at 90-94% efficiency, meaning 90-94p of every pound spent on gas is converted to useful heat. Older boilers may be only 60-75% efficient, wasting 25-40% of the gas consumed. Reducing your thermostat by just 1 degree C can save up to 10% on your heating bill, typically £80-£120 per year.

This calculator estimates your gas costs based on your boiler type and efficiency, thermostat setting, insulation level and property size. It shows monthly and annual costs and models the saving from upgrading your boiler or improving thermostat management.

UK gas prices 2026. Ofgem Price Cap unit rate: 5.5-7p/kWh (variable by quarter). Standing charge: 30-40p/day (£110-£146/year). Fixed tariffs available: 1-2p/kWh below Price Cap. Smart meter tariffs: similar to electricity but less time-of-use variation. Average UK gas usage: 12,000-14,000 kWh/year (typical 3-bed semi-detached). Annual bill £650-£1,000 + standing charge.

Heating cost by home type. 1-bed flat (well-insulated): 6,000-8,000 kWh/year = £350-£550 gas. 3-bed semi (typical UK): 12,000-14,000 kWh = £700-£950. 4-bed detached: 16,000-20,000 kWh = £900-£1,400. Solid-wall Victorian terrace (poor insulation): 18,000-25,000 kWh = £1,000-£1,750. Heat pump replacement: 75-80% reduction in gas usage but uses electricity 3-4 kWh/kWh — about same or slightly lower running costs.

Gas vs electric heating costs. Per kWh: gas 6p; electricity 28p. Surface comparison: electric 4.5× expensive. BUT: heat pumps deliver 3-4 kWh heat per 1 kWh electricity (COP 3-4). Effective: gas 6p/kWh heat vs heat pump 7-9p/kWh heat. With Octopus Cosy tariff (off-peak 12p): heat pump can be 3-4p/kWh heat — CHEAPER than gas. Storage heaters on Economy 7: 11p/kWh off-peak — about 2× gas but no installation cost.

Reducing gas costs. Loft insulation (270mm): saves £200-£500/year. Cavity wall insulation: £300-£500/year. Draught-proofing: £40-£120/year. Hot water tank insulation: £50/year. Thermostat 1°C cooler (19°C vs 20°C): saves 10% gas. TRVs (Thermostatic Radiator Valves): £100-£200 saving if rooms heated independently. Smart thermostat (Nest, Hive): £50-£150/year. Combine: total typical UK home saving £600-£1,200/year by efficiency measures.

Heat pumps and Boiler Upgrade Scheme. Boiler Upgrade Scheme (BUS): £7,500 grant for air-source heat pump installation (raised from £5,000 in October 2023). Typical installed cost: £8,000-£14,000 BEFORE grant. After grant: £500-£6,500 net cost. Eligible: replacing fossil fuel boiler in single-occupancy property; minimum insulation standards (loft, cavity). Running costs: 3-4× efficient — usually similar or lower than gas. Best fit: well-insulated home; underfloor heating or large radiators; non-restrictive planning.