The Secret to Selecting the Perfect Fireplace Size

Fireplaces have become increasingly popular, seeing a resurgence in popularity in recent years – fuelled in part by a need to return to a more wholesome, rural lifestyle, and as a pursuit of a better heat source for our homes. 

Fireplace Size Vs Room Size

What many might not realize however, is the extent to which the size of the room can limit the size of the fireplaces you can feasibly have. 

But how exactly does it work, and what fireplace sizes are safe according to the size of the room? 

Why Are They So Popular? 

There are many reasons why, in recent years, fireplaces have become such a popular addition to the homes of many people. 

Better Heat Source

Firstly, they are better sources of direct heat – at least in the particular room you are spending the most time in. 

While gas and centralized heating circulates and disperses the hot air around the home, this can be ineffective, and can often seem colder than more traditional methods.

With a fireplace, you can create a more effective hub of heat within your main living spaces – perfect for those winter nights in front of the TV. 


Having a fireplace is also cheaper than gas and electricity – meaning that those with cheap access to wood and coal can heat their homes without breaking the bank to pay the gas and electric companies. 

This is much more suited to rural living, but it is also becoming more common in more populated areas as well. 


Many people also like the wholesome, rural image that a fireplace conjures – something that has become an even more powerful image as the ‘country living’ design style has grown in popularity. 

People like the notion of cozy, comfortable, simple living, and in an age where things have become increasingly modern, this image feels more and more appealing. 

Statement Pieces

From a design point of view, they are also a statement piece that can complete and bring together the feel of a room in your home – creating a central focus to any space. 

How Does Room Size Affect Fireplace Size? 

Unfortunately, while everyone might like the idea of a big roaring fireplace, this is not always a feasible outcome – especially if the dimensions of the room in question are simply too small for it to work. 

Proximity To Fire

Firstly, if the room is too small, then having a fireplace can be a serious safety issue, and one that could result in a house fire, injury, and even death.

This is why safety standards are in place, clearly defining what is considered acceptable and what isn’t. 

Lack Of Ventilation

With smaller rooms, there is also a distinct danger of smoke inhalation, as well as the consumption of toxins such as carbon monoxide that can prove fatal if not properly checked. 

This is because smaller rooms – especially those full of junk – have much less ventilation than larger spaces, meaning you are exposed to a more concentrated concoction of smoke and chemicals. 

Bad Aesthetics

The size of the fireplace can also prove to be aesthetically bad, especially if it is too large or too small for the space you have put it in.

This can have the opposite effects to the relaxing, statement piece that most people shoot for, and can make a room feel cluttered and unkempt. 

How Big Should A Fireplace Be? 

When it comes to picking the right size fireplace for your room, there are numerous things to consider – all of which your contractor can probably explain to you in more detail when the time comes. 

Calculating The Right Size

Fireplace Size Vs Room Size (1)

Luckily, there is a calculation you can use to establish the dimensions of your living space, and discover what fireplace will suit you best.

First, measure the length, width, and height of the particular room. Once you have all of these measurements, multiply them together to get the volume of the room. This looks a little like this: 

Length x width x height = volume

Once you have the volume of the room, the trick then is to multiply this number by 4. This will reveal the close minimum heat output that you can feasibly have in that space. This looks a little like this: 

Volume x 4 = minimum BTUs

What Does BTU Stand For? 

BTU stands for ‘British Thermal Units’, which is a metric used to measure heat – particularly that which is output from air conditioners, heating units, and fireplaces. 

What Sizes Can Fireplaces Come In? 

Generally speaking, fireplaces are available within three size categories – although if you are having one custom made, then this might be different slightly. 

The three measurements tend to be small, medium, and large – with these equating to the following: 

  • Small – 24”x24” (dimensions) – 10,000 to 18,000 BTU (approximate heat output)
  • Medium – 36”x30” (dimensions) – 25,000 to 30,000 BTU (approximate heat output)
  • Large – 48”x32” (dimensions) – 35,000 to 40,000 BTU (approximate heat output)

Generally speaking, the average size of a fireplace will be within the medium range, and will usually be within those above dimensions. 

What About Fireplace Inserts? 

The fireplace insert itself is usually measured in inches, and refers to the width of the insert from left to right.

These can tend to range anywhere from 20” to 60” in total – although as we have said, this can vary depending on your chosen design. 

Heat Output Vs Room Size

Of course, it is also important to understand British Thermal Units, and how this relates to heat output in terms of square footage. 

The following is a rough approximation of these figures: 

  • Small – 10,000 to 18,000 BTU – heats approximately 800 square feet (max)
  • Medium – 25,000 to 30,000 BTU – heats approximately 1400 square feet (max)
  • Large – 35,000 to 40,000 BTU – heats approximately 1800 square feet (max)

How Do You Work Out Square Footage? 

When working out the square footage of your home, or indeed of the living space in question, you can use the following equation: 

Length x width = square footage

By using this simple equation, you can work out which heat output would suit your space, and thus what fireplace will suit you best. 

What Else Determines Fireplace Size? 

There are also a few other factors that determine fireplace size. 


If you live in a relatively moderate climate, then you do not necessarily need a large fireplace, and can probably manage with a smaller, cheaper model. 

Alternatively, if you live in a colder environment, and the fireplace will be your primary source of heat for your living space, then it is really important to ensure that you factor this into the decision making process – as you might regret it come winter time!

Fireplace Type

The type of fireplace you want also plays a role. Some have larger surrounds, others have more intricate engravings, and these need to be factored in. 

This also is determined by whether it is an electric fire, a gas fire, or indeed a wood or coal fire – as each of these requires different dimensions, levels of space behind the fireplace, and enough room for the respective accompaniments than come with them. 

Final Thoughts

And there we have it, everything you need to know about room size, and the impact it has on the fireplace sizes available to you. 

There are many different options in modern times, allowing those with all manner of unusual room sizes to have the fireplace of their dreams – design features that are becoming much more popular in recent years. 

So if you are looking to install a fireplace in your home, be sure to factor in the above information!

Stevie Morris