Central heating cost calculator
At the 1 October to 31 December 2026 price cap gas rate of 7.97p per kWh, every kWh of heat from a gas boiler costs about 9.1p. Work out what your heating costs per hour, per day and over the winter.
CalculatorUpdated
Defaults from our sources, last updated 2026-11-02.
Estimates only, not financial advice. Results use average UK figures and the assumptions shown. Your real costs depend on your home, tariff, region and installer quotes. Always get several quotes from certified installers and check current tariff rates before deciding. Don't rely on these results alone: see our disclaimer.
How the cost is worked out
A boiler burns gas to make heat. If your home takes in 5 kW of heat for an hour, that's 5 kWh of heat. A boiler that is 88% efficient needs about 5.7 kWh of gas to make it, which at 7.97p costs about 45p. So the cost per hour is the heat output (kW) divided by the efficiency, times the gas price.
The figure that matters is the heat your home actually draws, not the number on the boiler. A 24 kW or 30 kW combi boiler is sized to heat hot water for taps quickly. When it heats radiators it usually runs well below its maximum, and the room thermostat switches it off once the house is warm. The 5 kW, 5 hours a day and 150 days a year defaults are our own example figures, not published averages, so change them to suit your home.
Cost per hour by heat output
| Average heat output | Gas used per hour | Cost per hour | Per day (5 hours) | 150 days |
|---|---|---|---|---|
| 3 kW | 3.4 kWh | 27p | £1 | £204 |
| 5 kW | 5.7 kWh | 45p | £2 | £340 |
| 8 kW | 9.1 kWh | 72p | £4 | £543 |
| 12 kW | 13.6 kWh | 109p | £5 | £815 |
| 24 kW | 27.3 kWh | 217p | £11 | £1,630 |
At the 1 October to 31 December 2026 price cap average gas rate of 7.97p/kWh (including 5% VAT), 88% boiler efficiency (our estimate for a modern condensing boiler in real use). Standing charges are extra: 29.68p a day for gas, paid whatever you use.
Check it against your bill
The most reliable figure is your own gas use, shown on your bill or app as kWh per year. Ofgem's typical (medium) household uses 9,500 kWh of gas a year for heating, hot water and cooking. At today's cap that costs about £865 a year including the standing charge. If the calculator's yearly result is far above your actual gas use, lower the heat output or hours. Work out your full bill with the energy bill calculator.
Gas vs electric heating: cost per kWh of heat
| Heating | Fuel price | Cost per kWh of heat |
|---|---|---|
| Gas boiler (88% efficient) | 7.97p | 9.1p |
| Heat pump (efficiency 3) | 26.32p | 8.8p |
| Plug-in electric heater | 26.32p | 26.3p |
Gas heat costs about a third as much as heat from a plug-in electric heater. A heat pump at an efficiency of 3 lands close to gas; in practice it depends on how efficient your heat pump is and on your tariff. Compare in detail with our heat pump vs gas running cost calculator and see what plug-in heaters cost with the electric heater calculator.
Ways to cut what heating costs
- Turn the thermostat down. The Energy Saving Trust suggests the lowest comfortable temperature, which for most people is 18°C to 21°C. It says turning it down one degree, from 22°C to 21°C, could save about £120 a year in Great Britain.
- Use your controls. According to the Energy Saving Trust, installing and using heating controls (a programmer, room thermostat and radiator valves) effectively could save around £100 a year in Great Britain.
- Don't turn the thermostat up when it's cold outside. The Energy Saving Trust notes the house heats to the set temperature anyway; it may just take longer, so set the heating to come on a little earlier instead.
- Lower the boiler's flow temperature if your radiators still heat the house well. The Energy Saving Trust explains that a lower return temperature helps the boiler work more efficiently.
- If you qualify, the Warm Home Discount takes £150 off your electricity bill this winter.
Frequently asked questions
How much does central heating cost per hour?
It depends on how much heat your home draws. At 7.97p per kWh of gas and 88% efficiency, each kW of heat costs about 9.1p an hour, so a home drawing 5 kW pays about 45p an hour while the boiler is running.
Does a 24 kW boiler burn 24 kW worth of gas an hour?
No. The rating is the boiler's maximum, mostly needed for instant hot water on a combi. When heating radiators it usually runs at a lower output and switches off when the thermostat is satisfied.
Is it cheaper to leave the heating on low all day?
Usually not. The Energy Saving Trust recommends using a programmer to switch the heating off when you're out or don't need it, and a lower setback temperature (it gives 12°C to 15°C as an example) to stop the home getting too cold. Keep a higher minimum if someone at home is older or has a health condition.
Is gas central heating cheaper than electric heaters?
Per unit of heat, yes: about 9.1p per kWh from gas against 26.32p from a plug-in heater at current cap rates. A small heater in one room for a short time can still cost less than heating the whole house.
Does this include the standing charge?
No. The calculator covers the gas you burn for heating. The gas standing charge (29.68p a day at the average cap) is paid whatever you use.
Sources
- Ofgem – Energy price cap unit rates and standing charges (1 Oct–31 Dec 2026)
- Ofgem – Changes to the energy price cap, 1 October to 31 December 2026
- Ofgem – Typical domestic consumption values (2026)
- Energy Saving Trust – Thermostats and heating controls
- Energy Systems Catapult – Electrification of Heat Demonstration Project final reports (DESNZ-funded)
Estimates only, not financial advice. Results use average UK figures and the assumptions shown. Your real costs depend on your home, tariff, region and installer quotes. Always get several quotes from certified installers and check current tariff rates before deciding. Don't rely on these results alone: see our disclaimer.