Electric Heater Cost Per Hour UK: Complete Guide

How to Calculate Electric Heater Cost Per Hour

The formula is simple: divide the heater's wattage by 1,000 to get kilowatts, then multiply by the electricity rate in pence per kWh.

Every electric heater has a wattage rating printed on its label or in the manual. This tells you the maximum power it consumes when fully on [S1]. To find the cost per hour, use this formula: Cost per hour (pence) = (Wattage ÷ 1,000) × Electricity rate (pence per kWh).

At the current UK energy price cap, the electricity rate is 26.32p per kWh [S2]. This rate applies to all electricity usage up to the cap threshold. Standing charges are separate and payable regardless of heater use, so they are excluded from this calculation.

• Find your heater's wattage on the label or in the manual
• Divide wattage by 1,000 to convert to kilowatts
• Multiply by the electricity rate per kWh (currently 26.32p)
• Result is the cost in pence per hour at maximum power
• Standing charges are excluded as they are payable regardless [S2]

Cost by Heater Type

Different heater types have different typical wattages, but the calculation formula remains the same for all electric heaters.

Fan heaters are typically rated at 2kW and heat a room quickly, but they only provide heat while actively blowing air [S3]. Oil-filled radiators are also commonly 2kW, but their thermostat cycles the element on and off, so average consumption is lower. Panel heaters range from 1-1.5kW and are designed for background heating.

Convector heaters and storage heaters have different characteristics. Storage heaters use cheap off-peak electricity (typically 15-20p per kWh on Economy 7/10 tariffs) to store heat overnight, then release it during the day [S4]. This can significantly reduce running costs compared to standard-rate electricity.

• Fan heater: typically 2kW, heats quickly but only while running
• Oil-filled radiator: typically 2kW, thermostat cycles reduce average consumption
• Panel heater: typically 1-1.5kW, good for background heating
• Convector heater: typically 2kW, similar to fan heaters
• Storage heater: uses off-peak electricity at 15-20p/kWh [S4]

Why Oil-Filled Heaters Cost Less to Run

Oil-filled radiators cost less on average because their thermostat cycles the heating element on and off, rather than running continuously.

An oil-filled radiator rated at 2kW does not actually consume 2kW continuously [S3]. Once the oil reaches the set temperature, the thermostat switches the element off. The oil continues to radiate heat while cooling, and the element only reactivates when the oil temperature drops below the set point.

In a well-insulated room, the element may only be on for 50-70% of the time, reducing average consumption to 1-1.4kW. This makes oil-filled radiators more economical for extended heating periods compared to fan heaters, which consume full wattage whenever switched on.

• Oil acts as a thermal battery, retaining heat after element switches off
• Thermostat cycles element on/off, reducing average consumption
• In well-insulated rooms, element may only run 50-70% of the time
• Fan heaters consume full wattage whenever on
• Oil-filled radiators are better for overnight or all-day heating

Impact of Electricity Rate Changes

The cost per hour changes with the electricity rate. When the Ofgem cap changes, your heater costs change proportionally.

The Ofgem energy price cap is reviewed quarterly and can change [S2]. When the cap increases, your heater costs increase proportionally. For example, at 30p per kWh, a 2kW heater costs 60p per hour instead of 52.6p. At 24p per kWh, the same heater costs 48p per hour.

To calculate costs at your actual rate, check your electricity bill or smart meter app for the unit rate in pence per kWh, then apply the formula [S1]. Some tariffs offer lower rates during off-peak hours, which can significantly reduce costs for storage heaters and timed heating.

• Ofgem cap rate (2026): 26.32p per kWh [S2]
• At 30p/kWh: 2kW heater costs 60p per hour
• At 24p/kWh: 2kW heater costs 48p per hour
• Off-peak tariffs (Economy 7/10): typically 15-20p per kWh
• Check your actual rate on your electricity bill or smart meter app

Tips to Reduce Electric Heater Running Costs

Simple adjustments like lowering the thermostat, using a timer, and improving insulation can significantly reduce electric heater costs.

The most effective way to reduce electric heater costs is to use less heating overall. Lowering your thermostat by just 1°C can reduce heating costs by approximately 10% [S4]. Combine this with better insulation and draught-proofing to keep heat in the room longer.

Use a timer to heat the room only when needed, rather than leaving the heater on all day. Heat the room 30 minutes before you need it and switch off 30 minutes before you leave. This takes advantage of the thermal mass of the room retaining heat after the heater switches off.

• Lower thermostat by 1°C to save approximately 10% on heating costs [S4]
• Use a timer to heat only when needed
• Close doors to heat only the room you are using
• Improve insulation and draught-proofing to retain heat
• Use a rug on hard floors to reduce heat loss through the floor
• Consider off-peak tariffs for storage heaters [S4]

Weekly and Monthly Cost Estimates

Running a 2kW electric heater for 4 hours daily costs approximately £14.73 per week or £63 per month.

To estimate your weekly cost, multiply the hourly cost by the number of hours per day and then by 7. For a 2kW heater running 4 hours per day at 26.32p/kWh: 52.6p × 4 hours × 7 days = £14.73 per week.

Monthly costs follow the same pattern: £14.73 × 4.33 weeks = approximately £63 per month [S1]. However, real-world costs are often lower because thermostats cycle the heater off periodically. A more realistic estimate for a thermostatically controlled heater is 60-80% of the maximum calculation.

• 2kW heater, 4 hours/day: £14.73/week or £63/month
• 1.5kW heater, 4 hours/day: £11.05/week or £47/month
• 1kW heater, 4 hours/day: £7.37/week or £32/month
• Thermostatically controlled heaters average 60-80% of maximum
• Actual costs depend on room insulation and thermostat settings

Frequently asked questions

Bottom line

The cost of running an electric heater depends on its wattage and your electricity rate. At the current UK cap rate of 26.32p per kWh, a 2kW heater costs 52.6p per hour at maximum power. Oil-filled radiators with thermostats cost less on average due to cycling. To minimise costs, use a timer, heat only the room you need, and improve insulation.