The Proper Way to Measure Dimensions of a Fireplace

In order to measure your fireplace, you will need to record the height, width, and depth. Failing to record the proper dimensions can lead you to purchase an insert that will not fit correctly. To do this, you will need to record each dimension at different points to get an accurate reading. Firebox, fireplace opening, or cavity, it’s all the same! These names all refer to the same thing. I just depends on the jargon you’re using. Let’s get started!

How to Measure a Fireplace

How to Measure a Fireplace Opening

Now the quick way to do this would be to take the height and width of the fireplace and call it a day right? Wrong! In order to pull the correct dimensions, you need to measure your fireplace cavity at different points to ensure that there aren’t any areas that are smaller than others.

Measuring a Firebox

Figure 1.1: The opening width of this firebox is 42 3/4″ at the face of the unit and the height is 35 1/4″. These are exterior measurements; interior measurements also need to be taken. Directions on recording interior dimensions are round below.

*Sometimes, small architectural blemishes can lead to tight fittings! Standard fireplace inserts will fit into existing fireboxes but it’s always a good idea to check to make sure*

Height – Up and Down

Using measuring tape, record the height of your firebox from the opening, the rear and the lintel (more on this in the next paragraph). If you have a fireplace with and arched opening, make sure you take down the dimensions at the highest and lowest points. Generally speaking, you want to use the smallest of these measurements for your final report.

Some brick fireplaces have what’s called a lintel. A lintel is an iron rod that runs from the front to back down the ceiling of your fireplace opening. The purpose of the lintel is to provide structural support for your fireplace and is usually embedded in the brick but can sometimes be visible. If you’re opening has a lintel that is protruding slightly, make adjustments for the lintel and add 1/8” space to create sufficient room for clearance.

Measure Fireplace Width and Height

Here we can see that the interior width of this fireplace in the rear is 26″ and the interior height is 18″.

Width – Left to Right

In a similar fashion, you will need to measure the width of your firebox from the opening (aka the face or exterior measurement) and rear (interior). Cross-check the width at different heights to make sure your firebox is symmetrical. Theoretically speaking, the width should be the same at all point on square fireboxes but fireplaces with angled sidewalls will have different dimensions based on where you take your measurements.

Depth – Front to Back

The depth is the distance from the face of your firebox to the back wall. Record the dimensions of your fireplace depth from the center of your firebox.

Making Sure Your Measurements are Accurate

Fireplace Dimensions

Click here to print out this chart to keep track of all of your measurements!

Now that you have all of the dimensions for your firebox, check back with these inserts to make sure that your readings are somewhat similar. If you have any questions, feel free to give us a ring so we can clear things up for you! Reach us at 1-888-682-2591!

When deciding on the right electric fireplace insert for your home, always use the smallest dimensions. This way, your insert will fit snugly without having to force it in. Failing to do so could necessitate some modifications on your existing fireplace opening. Do it right the first time!

45 inch Dimplex Direct Wire Built-in Purifire Firebox

The 45″ Dimplex Direct Wire Firebox with Built-in Purifire to filter the air inside your home! Learn More

To learn how to install your new electric fireplace insert, please refer to the following posts:

  1. How to convert a Gas Fireplace to an Electric Insert
  2. Convert Your Hearth to an Electric Fireplace