Electric Heater Running Cost Calculator
It's easy to underestimate how quickly an electric heater's running cost adds up over a week of regular use. Enter your heater's wattage, how many hours a day you run it, and your electricity rate below for a cost estimate.
Estimate your electric heater running cost
Enter your heater's wattage, how long you run it, and your electricity rate.
Using 8.00 kWh/day, this heater costs approximately:
£15.12 per week
That's around £64.80 per month at this usage level.
Recommended products
A few well-reviewed electric heaters.
£29.95
Pros
- 3 heat settings plus fan-only mode
- Built-in overheat and tip-over protection
- Strong review volume (2.7k ratings, 4.6★)
Cons
- No oscillation on this model
- Runs loud at max setting
£91.50
Pros
- Oil-free Thermocore tech for faster warm-up
- Adjustable thermostat with 3 heat settings
- Castors for portability, overheat/safety shut-off
Cons
- Slower to warm a room than a fan heater
- Lower review count than other picks
£129.00
Pros
- Well-established premium oil-filled radiator line
- Enhanced chimney-effect heating, anti-frost thermostat
- Castors for mobility
Cons
- Heavier than column radiators without oil fill
- Stock can run low — check availability before buying
Frequently asked questions
Are electric heaters expensive to run?
Electric heaters convert nearly all their electricity directly into heat, so running costs scale directly with wattage and hours used — a 2kW heater running for several hours a day adds up quickly compared with central heating covering the same space more efficiently.
Is it cheaper to heat one room with an electric heater than the whole house with central heating?
It can be, if you genuinely only need to heat a single occupied room for a short period, since you avoid heating empty rooms. But running an electric heater for many hours a day is often more expensive per unit of heat than gas central heating, so it works best for occasional, targeted use.
Do all electric heaters use the same amount of electricity for the same wattage?
Yes — a 2000W heater uses 2000W of electricity regardless of the heating technology (fan, oil-filled, ceramic, halogen), since wattage is a direct measure of electrical input. What differs between types is how evenly and how long that heat is retained in the room.
Does a thermostat on an electric heater reduce running costs?
Yes — a heater with a thermostat cycles off once the room reaches the set temperature rather than running continuously at full power, which can meaningfully reduce the average hourly cost compared with a heater running flat out the whole time.
How this calculator works
The calculator uses a simple formula: Energy Consumption (kWh) = Power (Watts) x Time (Hours). You input the wattage of the electric heater you're considering – typically found on the product label or in the specifications. Then, you estimate how many hours per day you intend to run it. The calculator multiplies these two figures together to determine the daily energy consumption in kilowatt-hours (kWh).
This kWh figure is then multiplied by your current electricity price per kWh to calculate the total daily cost. Current UK average residential rates fluctuate but as of late 2024, you’re looking at around £0.3 - £0.35 per kWh depending on your energy provider and tariff. The calculator provides an estimated cost based on this industry standard; always check your own electricity bill for the most accurate figures.
Key Factors Affecting Running Costs
- Room Size: A larger room will require a higher wattage heater to achieve the same level of warmth, increasing energy consumption.
- Insulation Levels: Poorly insulated homes lose heat faster, requiring longer running times and higher wattages for an electric heater to maintain a comfortable temperature.
- Thermostat Setting: Lowering your thermostat setting by just 1°C can reduce heating costs by up to 8%. Consider using a smart thermostat to optimise heating schedules.
- Heater Efficiency Rating (W/K): This rating indicates how effectively the heater converts electricity into heat. Higher ratings mean lower running costs for the same output.
- Usage Patterns: Heating for short periods is generally cheaper than running a heater continuously throughout the day. Smart scheduling can minimise wasted energy.
- External Temperature: The colder it is outside, the more energy your heater will need to expend to maintain a comfortable indoor temperature.
Worked example: A Fireside 2000W Radiator
Let’s say you're considering purchasing a Fireside 2000W fan heater. You plan to run it for 4 hours each day during the colder months. Using our calculator, we input 2000 Watts and 4 hours. This yields a daily energy consumption of 8 kWh (2000 x 4 = 8000, then divided by 1000).
Assuming an average electricity price of £0.35 per kWh (check your bill!), the daily cost would be £2.80 (8 x 0.35 = 2.80). Over a month with 30 days, the total estimated running cost would be £84.00. Remember this is an estimate – actual costs will vary depending on usage and your energy tariff.
More questions answered
What does 'Watt' actually mean?
Watt is a unit of power, measuring the rate at which electrical energy is used. It’s often confused with ‘heat output’, which measures how much heat a heater produces. A higher wattage doesn’t always equal more heat; efficiency plays a crucial role.
How does my electricity tariff affect the cost?
Your electricity tariff determines the price you pay per kWh. Standard variable tariffs currently average around £0.35/kWh, but fixed rates or economy tariffs can be significantly lower. Compare different tariffs to find the best deal.
Should I round up or down when entering the hours?
It’s best to use whole numbers for the ‘hours’ input. Rounding up slightly will overestimate costs, while rounding down could lead you underestimating your usage – it's better to err on the side of caution.
What if I only run the heater intermittently?
Estimate your typical running time as accurately as possible. Even short bursts of heat add up over time. Consider setting a timer for shorter periods rather than leaving the heater running continuously.
Can I use this calculator to compare different electric heaters?
Yes, absolutely! Simply input the wattage of each heater and your desired usage time to get an accurate comparison of their estimated running costs. This will help you choose a model that fits your budget.
What is kWh and why does it matter?
Kilowatt-hour (kWh) is a unit of energy, representing 1000 watts consumed for one hour. It’s the standard unit used to measure electricity consumption, and accurately calculating kWh is essential for determining running costs.
Are there any hidden costs I should consider?
Besides electricity, factor in potential maintenance costs (like filter replacements) or the cost of replacing an old heater with a newer, more energy-efficient model.
My calculated cost seems too high – what am I doing wrong?
Double-check your wattage input and usage time. Ensure you're using the correct electricity price per kWh (your bill will show this). Consider insulation levels in your room.
Can I use this calculator to plan for winter?
Yes! Use the calculator regularly as heating needs change throughout the year. Regularly updating your estimates based on weather forecasts and your usage habits will help you manage your energy costs effectively.
What's the difference between a fan heater and a radiant heater?
Fan heaters circulate air, warming the room quickly but often with higher electricity consumption. Radiant heaters directly heat objects and people in the room, generally being more efficient for smaller spaces – check their wattage ratings carefully before comparing.