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Enter your gas fire kW rating and daily usage below to instantly calculate running costs per hour, day, week, month and year using the current Ofgem gas rate of 6.24p/kWh.
Common fire ratings:
Per Hour
£0.22
Per Day
£0.87
Per Week
£6.12
Per Month
£26.21
Per Year
£318.86
Formula: Cost = kW x hours x (rate / 100). Based on 4 hours of use per day.
Important: Please rely on a professional, accredited Gas Safe engineer and accredited tools for all measuring. This calculator provides estimates only and accepts no liability for calculations.
The running cost of a gas fire depends primarily on its kW rating and how many hours you use it each day. Typical UK gas fires range from 2kW to 7kW, with most living room fires falling in the 3-4kW range.
At the current Ofgem gas unit rate of 6.24p/kWh, a typical 3.5kW gas fire costs approximately 22p per hour to run. Over a 4-hour evening, that works out to around 87p per day, or roughly £26.21 per month.
The table below shows estimated running costs for common gas fire sizes at 6.24p/kWh, based on 4 hours of use per day:
| Fire Size | Type | Per Hour | Per Day (4h) | Per Month |
|---|---|---|---|---|
| 2 kW | Decorative | £0.12 | £0.50 | £14.98 |
| 3 kW | Decorative / Balanced Flue | £0.19 | £0.75 | £22.46 |
| 3.5 kW | Balanced Flue | £0.22 | £0.87 | £26.21 |
| 5 kW | Balanced Flue / Open Flue | £0.31 | £1.25 | £37.44 |
| 7 kW | Open Flue | £0.44 | £1.75 | £52.42 |
Costs based on the Ofgem price cap gas rate of 6.24p/kWh effective January 2026. Actual costs may vary depending on your tariff and gas fire efficiency.
Not all gas fires are created equal. The type of gas fire you have significantly affects both its running cost and how effectively it heats your room. Here are the main types found in UK homes:
Typical rating: 2-3 kW
Decorative gas fires are designed primarily for aesthetics rather than heating. They produce a realistic flame effect but deliver the lowest heat output of any gas fire type, making them the cheapest to run.
Estimated hourly cost
12p - 19p
Efficiency: 50-60%
Typical rating: 3-5 kW
Balanced flue gas fires draw air from outside and expel combustion gases through a sealed flue system. They are the most efficient type of gas fire, with ratings typically between 80-90%.
Estimated hourly cost
19p - 31p
Efficiency: 80-90%
Typical rating: 5-7 kW
Open flue gas fires use the room's air for combustion and vent through a chimney or flue. While they produce the most heat, they are the least efficient as much heat escapes up the flue.
Estimated hourly cost
31p - 44p
Efficiency: 55-65%
The efficiency rating of a gas fire tells you how much of the gas energy is converted into useful heat for your room. A fire rated at 80% efficiency converts 80p of every £1 of gas into heat, with the remaining 20p lost through the flue or casing.
This means a 3.5kW balanced flue fire at 85% efficiency delivers roughly 3kW of useful heat to your room, while a 5kW open flue fire at 60% efficiency only delivers about 3kW of useful heat despite consuming more gas. Always consider efficiency when comparing gas fire running costs.
One of the most common questions homeowners ask is whether a gas fire is cheaper to run than an electric heater. The answer depends on energy prices, appliance efficiency, and how you use each one.
Gas is approximately 4 times cheaper per kWh than electricity (6.24p vs 24.5p). While electric heaters convert 100% of electricity into heat compared to 60-90% for gas fires, the raw price difference is so large that gas fires are still significantly cheaper to run in almost every scenario.
Even a relatively inefficient open flue gas fire at 60% efficiency has an effective cost of around 10p per kWh of useful heat, which is still less than half the cost of an electric heater. A high-efficiency balanced flue gas fire at 85% delivers heat at roughly 7p per kWh — over 3 times cheaper than electric.
* Effective cost per kWh of heat = unit rate / efficiency. Gas at 6.24p with 80% efficiency = 6.24 / 0.80 = 7.8p per kWh of useful heat delivered to the room.