How the heating cost calculator works

The calculator turns power, time and price into a running cost. It uses the same sum an energy supplier uses to bill a household: the kilowatt-hours used, multiplied by the unit rate in pence. Every figure on this page is an estimate, but it is built from the real price cap rates rather than a guess, and the result can be recalculated instantly with the unit rate from an actual energy bill.

For electric heaters the maths is simple, because a 2kW heater draws 2kW whenever the element is on. For gas central heating and heat pumps the calculator asks how much heat the home needs each hour, then works out how much gas or electricity is bought to make that heat. A gas boiler at 90% efficiency needs 1.11 kWh of gas for every 1 kWh of heat, and a heat pump with a seasonal efficiency of 3.0 needs only 0.33 kWh of electricity for the same kWh of heat.

The standing charge is left out on purpose. It is a fixed daily amount paid whether or not a heater is switched on, so it does not change the cost of running a particular heater. It does matter for the overall bill, and the figures are covered below.

UK energy price cap rates, October to December 2026

Ofgem sets the maximum unit rate and daily standing charge that suppliers can charge on default tariffs, and reviews them every three months. From 1 October to 31 December 2026 the cap rose by 4%, taking the typical household bill from £1,663 to £1,723 a year for dual fuel paid by Direct Debit. Higher wholesale gas prices linked to the Middle East conflict drove the increase. The full explanation of how the cap is worked out is in the guide to what the energy price cap is and how it works.

Two details change what the cap means in practice. First, electricity VAT has been removed until the end of March 2027, which keeps the electricity unit rate lower than it would otherwise be. Ofgem estimated that without the VAT cut the cap would have been around £45 a year higher. Second, the standing charges add up: 54.83p a day for electricity is roughly £200 a year and 29.68p a day for gas is roughly £108 a year, before a single unit of energy is used.

Homes on fixed tariffs are not affected by the cap until the deal ends, and homes heated by heating oil or LPG are outside the price cap entirely. Oil and LPG households can read the separate guide to heating oil and LPG prices. Regional unit rates differ by a few pence, and the Price of a Warm Home Index shows what heating costs in different parts of the UK.

How much does an electric heater cost to run per hour?

An electric heater costs its wattage in kilowatts multiplied by the unit rate. At the current cap of 26.32p per kWh, a 1kW heater costs about 26p an hour, a 2kW heater about 53p an hour and a 3kW fan heater about 79p an hour. Electric heaters are close to 100% efficient at turning electricity into heat, so the type of heater makes less difference to the bill than its wattage and the number of hours it runs.

How much does a 2kW electric heater cost per hour?

A 2kW heater costs about 53p an hour at the current price cap. Run for four hours a day, that is about £2.11 a day, £14.74 a week and £63.87 a month. If the cap rises by around 16% in January 2027, as some forecasters expect, the same heater would cost about 61p an hour.

How much does an oil-filled radiator cost to run?

An oil-filled radiator costs the same per hour as any other electric heater of the same wattage. On a 600W low setting it costs about 16p an hour, and at the full 1,500W it costs about 39.5p an hour. Oil-filled radiators can work out cheaper in practice because the oil keeps giving out heat after the thermostat switches the element off, so the element runs for only part of each hour.

How much does a panel heater cost per hour?

A 500W panel heater costs about 13p an hour and a 1,000W panel heater about 26p an hour. Panel heaters with a good thermostat and a timer suit small rooms and short periods of use. For the full comparison with another low-cost option, see heated blanket vs electric heater.

How much does a fan heater cost per hour?

A fan heater on its highest 3kW setting costs about 79p an hour, which makes it the most expensive common heater to run. It heats the air quickly but gives no lasting warmth, so it is best used for short bursts rather than for hours at a time.

How much does an electric blanket cost to run?

A typical electric blanket draws around 100W, which costs about 2.6p an hour. Eight hours of use costs about 21p. Warming the person rather than the room is the cheapest way to stay warm, and it is the subject of the heated blanket comparison.

How much does gas central heating cost per hour, day and month?

Gas central heating costs more per hour than a single electric heater because it heats the whole house, but each unit of heat is much cheaper. For a three-bed semi that needs about 10 kWh of heat an hour, a 90% efficient boiler uses about 11.1 kWh of gas an hour. At the cap rate of 7.97p per kWh that is about 89p an hour, £3.54 for four hours, and £107.45 a month if the heating runs four hours every day.

Real gas costs vary more than electric heater costs because a boiler does not run flat out. It fires, reaches the water temperature, then switches off until the radiators cool. A well-insulated home needs fewer firing cycles. A home that loses heat quickly keeps the boiler working for much longer, which pushes the real cost above the calculator figure for the same number of hours. The causes are covered in why houses lose heat quickly, and the house cold diagnostic helps pin down which one applies.

How to find the figure for your own home

The most accurate method is a smart meter or a gas meter reading taken before and after a heating session. The difference in kWh, divided by the hours the heating was on, gives gas used per hour. Multiply that by the efficiency of the boiler to get the heat figure the calculator asks for, or simply choose the closest home size from the presets.

Two quick fixes that lower gas costs

A radiator with cold patches at the top has trapped air, which makes the boiler run longer to reach the same temperature. The guide to how to bleed a radiator takes about ten minutes per radiator. In freezing weather, a modern condensing boiler can also stop heating altogether when its condensate drain freezes, which is explained in the guide to a frozen condensate pipe. Hidden gaps around doors, floors and windows also send heat outside, and finding draughts is one of the cheapest ways to cut the hours the boiler runs.

Gas vs electric heating vs heat pump: which is cheapest per kWh of heat?

Per unit of heat, a gas boiler and a typical heat pump now cost almost the same, and both are far cheaper than a plug-in electric heater. At the October to December 2026 cap, gas at 7.97p per kWh and 90% boiler efficiency delivers heat for about 8.9p per kWh. A heat pump with a seasonal efficiency of 3.0 delivers heat for about 8.8p per kWh. A plug-in electric heater delivers it for 26.3p per kWh.

Is it cheaper to heat one room with electric or the whole house with gas?

Heating one room with an electric heater is cheaper than heating the whole house with gas only when the central heating stays off. At the cap rates, 1kW of electric heating costs about 26p an hour, against about 89p an hour for a typical three-bed home on gas. One person working in one room for a few hours often saves money with a small heater and the radiators turned down elsewhere. A family using several rooms all day almost always does better on gas. An electric heater added on top of central heating costs extra and saves nothing. The longer comparison is in heating one room or the whole house.

Leave the heating on low or use a timer?

For most UK homes a timer costs less than leaving the heating on low all day, because a house leaks heat faster the warmer it is kept. The reasoning and the exceptions, such as very well-insulated homes and heat pumps, are in leave heating on low or use a timer. Whether a lower thermostat setting saves money is covered in does turning the thermostat down save money.

Why a real bill can be higher than the calculator suggests

When actual bills run above the calculator figure, the heating is usually on for longer than expected, or the home is losing heat faster than average. Other common reasons are standing charges, which add about £6 a week for dual fuel before any energy is used, an older boiler running below 80% efficiency, radiators out of balance, thermostat settings above 20°C, and hot water for showers and washing, which comes from the same boiler. Every extra degree on the thermostat adds several per cent to heating use, which is why the complete guide to keeping a UK home warm for cheap starts with settings and draughts before spending money on equipment.

Heating costs this winter: the price cap outlook for January 2027

The January to March 2027 price cap has not been set. Ofgem is due to announce it in late November 2026, and forecasts published since the October announcement point to another rise. Cornwall Insight has forecast a cap of around £1,999 a year for a typical household, and supplier forecasts reported in September and October range higher, up to about £2,165, compared with £1,723 now. Forecasts move with wholesale gas prices and can change before the announcement.

Because the forecast rise is mostly driven by gas, every heating type is affected. The January what-if button in the calculator applies a 16% increase to the unit rate as a rough guide only. When Ofgem confirms the new rates, this page is updated, and the earlier explainer on whether the Middle East conflict will push up bills is in Iran conflict and UK energy bills.

Ways to lower the bill before January

• Check whether a fixed tariff is cheaper than the price cap. The energy tariff comparison shows what is available, and fixed customers are not moved onto the new cap.
• Lower the thermostat by one degree and set a timer so the heating is off while nobody is in.
• Bleed radiators, balance the system and fix draughts, which cut the hours the boiler runs.
• Check whether a grant covers insulation or a heat pump. The energy grant checker shows which grants can be combined, and the Warm Homes Plan 2027 guide explains the new support and loans that are coming.

More practical guides are on the WarmGuide homepage, which brings together the tools, the price index and the winter heating guides.