What Size Stove or Fire Do I Need for My Room?

Choosing the correct heat output will help keep your room comfortable without making it too hot or leaving it underheated. Stove and fire outputs are measured in kilowatts, shown as kW.

Calculate the Size of Your Room

Start by measuring the:

• Length of the room
• Width of the room
• Height of the room

Multiply these measurements together to calculate the room volume in cubic metres:
Length × width × height = room volume in m³
As a rough guide, allow approximately 1kW of heat output for every 14m³ of space. Use the following calculation:
Room volume ÷ 14 = approximate heat output required

Example Heat Output Calculation

For a room measuring:

• 5 metres long
• 4 metres wide
• 2.4 metres high

The room volume would be:
5 × 4 × 2.4 = 48m³
The approximate heat requirement would be:
48 ÷ 14 = 3.4kW
A stove with an output of around 3.5kW may be suitable, although insulation and room layout should also be considered.

Consider the Level of Insulation

A modern, well-insulated room will normally retain heat for longer than an older property with limited insulation. You may need a higher output if the room has:

• Single-glazed windows
• Several outside walls
• Large windows or patio doors
• High ceilings
• Poor wall or loft insulation
• Open doorways into other rooms

A well-insulated room may need less heat than the basic calculation suggests.

Measuring an Open-Plan Room

Measure the complete area that the stove or fire will be expected to heat. For example, when a living room opens directly into a kitchen or dining area without doors, include all connected spaces in the calculation. Heat will move into the adjoining areas, so measuring only the section containing the stove could produce an estimate that is too low.

Why an Oversized Stove Can Be a Problem

Choosing the largest stove available will not necessarily heat the room more efficiently. An oversized wood-burning or multifuel stove may need to be continually turned down to stop the room from becoming uncomfortable. Operating a stove at a very low setting can also affect how cleanly and efficiently it burns. A correctly sized stove should be able to operate near its normal output while keeping the room at a comfortable temperature.

What About Gas and Electric Fires?

The same room calculation can provide a useful starting point when comparing gas and electric fires. Many electric fires are mainly used for their flame effect and occasional additional warmth rather than as the main source of heating. Check the heat output shown on the individual product page and consider how much warmth you expect the fire to provide.

Heat Output and Physical Stove Size

The physical size of a stove does not always indicate how much heat it produces. A wide stove may have a moderate heat output, while a more compact model could provide enough warmth for an average-sized room. Always check the stated kW output rather than choosing a stove by appearance alone. You should also make sure it fits safely within the fireplace opening and allows for the clearances required by the manufacturer.

Ask an Installer Before Ordering

This calculation provides an approximate guide only. A suitably qualified installer can assess the room, chimney, ventilation and proposed installation before confirming the correct stove output.
Please contact us if you need help comparing the heat outputs of our stoves or fires.