How to measure an electric fireplace insert

A fireplace can be a great addition to your home. The right electric fireplace insert will provide you with the warmth and ambiance of a fire without the mess or hassle of wood, gas, or coal. But before you can buy an insert for your fireplace, you need to measure it first. This blog post will show you how to measure for electric fireplace insert! 

There are many things to consider when measuring for an electric fireplace insert. The first thing is the width of the opening in which you plan on installing it. You should also measure your desired depth, height, and length.

How to measure an electric fireplace insert

Be sure to consider any other furniture that may be around the area where you want to install your new fireplace insert so that it does not interfere with them or make them difficult to reach or see past. Read on to know more!

What You’ll Need to Measure for Electric Fireplace Insert? 

Tools are provided with most electric fireplace inserts, but it’s recommended to have the following for an accurate measurement.

  • Measuring Tape
  • Rulers or straight edge
  • Cordless drill or screwdriver
  • Wood screws
  • Masking tape
  • Pencil
  • Fine-tip black marker.

Before you measure for your electric fireplace insert, be sure that there is enough room between the fireplace opening and the surrounding wall to fit your new insert.

Step by Step Guide: How to Measure for Electric Fireplace Insert

How to measure an electric fireplace insert

Step 1 – Find the Location to Install Your Electric Fireplace Insert

To determine how much space is needed around the electric fireplace insert, you will need to find out where it is going. The fireplace should be at least three feet from any heater or air conditioner so that the heat and cold air does not affect it.

To get an accurate measurement of the depth of your fireplace opening, be sure to include any tiles or trim that jut out from around it. This way, you won’t have to adjust for any obstructions when choosing an electric fireplace insert. Most inserts are designed to be cut away so they’ll fit perfectly in your fireplace.

Step 2 – Determine the Width of the Unit

You should measure the width of your fireplace opening as well as its height. This will help you to know if you need a standard or oversized electric fireplace insert. A standard unit will fit most fireplace openings, whereas an oversized one will have to be custom-built.

How to measure an electric fireplace insert

To find out how big your electric fireplace insert should be, first measure the height of your fireplace opening from the floor to the ceiling. Then, measure from the side of the mantle or shelf on top of the fireplace to the opposite side. These measurements will help you choose the right size insert for your fireplace.

Step 3 – Measuring for Depth

The next step for how to measure for an electric fireplace insert is to measure the depth of your fireplace opening. If you are installing a standard electric fireplace insert, the depth will be determined by the measurements from the previous step. For an oversized unit,

you’ll have to choose this yourself. Next, measure the depth of your fireplace opening from the front edge of the fireplace to the back wall.

Step 4 – Measuring for Height and Length

The subsequent measurements you’ll need to know before buying your electric fireplace insert are its height and length. The depth measurement will determine the standard size, but this step gives you a chance to adjust it as needed to fit.

How to measure an electric fireplace insert

To find the length of an electric fireplace insert that will fit your chimney, add two inches to the height of your fireplace opening and subtract one inch from the width.

Step 5 – Measuring for the Project

If you want to customize the electric fireplace insert further, then measure your project before buying it. These measurements will determine how much room you have around the unit and where any outlets should be placed. For example, to fit a standard-sized electric fireplace insert into a corner, measure from a measured point at the top of one side of the mantle or shelf to the top of the opposite side.

From that point, measure down two inches and then across to the top of the end on the other side. This measurement is how much room you will need around your electric fireplace insert for it to fit correctly.

Step 6 – Analyze the Open Space Around Fireplace

Take another look at the open space around your electric fireplace insert. Depending on where you are installing it, there may be obstructions or outlets that you’ll need to consider when buying your project.

If you’re planning to install your electric fireplace insert in a corner, make sure there’s enough space behind the unit for the cord to reach the outlet, and no obstructions in front of it. If your fireplace is built into a wall or shelf, you may need to cut away some parts so it fits properly.

Step 7 – Check the Outlet of Power Supply

If you install an electric fireplace insert in an area that already has appliances, you will need to check the outlet where you want to plug it in. Ensure that there is enough room between other devices for your electric fireplace insert’s cord and any extension cords or power strips. You should also ensure that the chimney does not contain any obstructions that may block the cable or restrict airflow.

How to measure an electric fireplace insert

Step 8 – Check for Proper Ventilation

Make sure that your area can support an electric fireplace insert before installing it. If the chimney is not vented correctly, then there won’t be enough air in the room to support combustion.

This will cause poor circulation and could damage your unit. Check that the chimney is clean and has an opening of at least 1.5 inches (3.8 cm) in diameter for your electric fireplace insert to work correctly.

Step 9 – Check the Mantle Dimensions

Before installing an electric fireplace insert, double-check the dimensions of your mantle or shelf. The right dimensions are crucial for a successful installation, as well as for providing enough room around the opening for wiring and airflow. When measuring the dimensions of your mantle, be sure to factor in any potential obstructions.

If you install an electric fireplace insert in a corner, make sure that it is at least 24 inches (61 cm) from any other protruding objects or walls. You may have to cut away shelving, or other parts of your chimney runs into another thing. Also, make sure that your mantle is sturdy enough to support the electric fireplace insert you are planning to buy.

Step 10 – Attaching It to Your Chimney

The last step for how to measure for an electric fireplace insert is attaching the chimney. If installing an electric fireplace insert in a corner, attach the vent directly to your wall or shelf. You will want to make sure that the mantel or shelf is solidly attached before doing so; otherwise, it may work itself loose over time and put extra weight on your electric fireplace insert.

If you install an electric fireplace insert into the side of your chimney, you can use screws or brackets to secure it. The mantel is only held in place by gravity, so this will give it added support and keep it more securely in place than adhesive or double-sided tape alone. You can find compatible brackets online or in most hardware stores.

How to measure an electric fireplace insert


This is a general step-by-step guide on how to measure for electric fireplace insert. Please get in touch with professional service for measurements if you are unsure about your specific project.

Alternative Ways to Measure for Electric Fireplace Insert:

To know how to measure for electric fireplace insert will vary slightly depending on the brand or style you are buying. However, most inserts have very similar measuring parameters. If you have a fireplace insert custom-made, then the measurements can be tailored to your specifications. Following are some general guidelines for various inserts-

1) Width –

The unit’s width should be measured in the center of the appliance, at the top. Do not measure at the outer edges; if you do, you will get an inaccurate measurement.

2) Height –

The height can be measured from one side to another side horizontally across the unit’s front panel. For instance, if your fireplace opening is 10″ high, measure the height at 8″ and 12″. This will ensure that your insert fits.

3) Depth –

This measurement should be done across the width of the front panel at two points: one in front and one in back. The depth of an electric fireplace insert is usually about 2″ to 4″, depending on the unit design.

How to measure an electric fireplace insert

4) Flue –

The flue height should be measured from the top of the unit to the centerline of the chimney. Do not forget to add in however many bends you have in your chimney or flue pipe. If you are using a flex liner, measure that as well.

5) Blower Power Cord Length –

Remember, this is measured from the back of the unit to the power outlet (and not all units will be located in front of an outlet). Also, do not forget about switch clearance if it is needed.

6) Hearth Depth –

The distance from the front of your insert to the beginning of the hearth is an important measurement. Usually, this will be at least 2″, but some inserts can even extend up to 4″ past the outer doors if desired.

7) Wood Side Clearance –

Measure the space between your wood sides. This can vary from 1/8″ to 1″, depending on your preferences, however, a good rule of thumb is about 3/16″.

8) Remote Control –

If you are going to be placing your electric fireplace insert by a wall switch or other control options, make sure to measure the distance from your preferred location and the required height of the remote receiver.

How to measure an electric fireplace insert

9) Flare –

The size of a fireplace unit is important for it to work properly. The flare is the distance from the front of the appliance to where the doors meet when they are closed. This measurement is critical for the unit to function correctly.

10) Brackets and Pillars –

Measure the height of your brackets, pillars, and any other decorative features you will be used to determine if they will fit into the opening.

Some factors can affect these dimensions, such as an angled opening or a raised stone hearth already in place. However, most electric fireplace inserts are standard dimensions. If you’re still unsure how to measure for electric fireplace insert, it will be best to hire a skilled person.

It is also important to remember that the height of the bottom sill of your fireplace opening determines how far down you can have your trim extend. If this height does not allow for your insert to sit flush with the rest of the mantel, then it will stick out and look awkward-so be sure to measure your opening carefully.

Some Helpful Tips and Suggestions:

1. If you want to measure for an electric fireplace insert, be sure that this is what you truly need. You may find the replacement of your current unit more practical.

2. Be sure to check whether or not your measurement can fit through doorways, hallways, and up/down staircases (if the unit needs to be transported).

3. Be sure to check the power rating on your unit. This will help you measure for an efficient and safe fireplace insert.

How to measure an electric fireplace insert

4. When measuring for an electric fireplace insert, use a steel tape measure. Do not rely on a cloth-style measuring tape as these can be inaccurate.

5. Measure the inside width and height of where the unit will be installed.

6. If you are trying to measure for an electric fireplace insert that needs both width and height, then measure the opening diagonally.

7. Be sure that you have plenty of space surrounding your unit to enjoy it fully. Also, make sure there are no obstructions nearby (walls/windows/etc.).

What Is the Standard Size for an Electric Fireplace Insert?

There is no standard size for an electric fireplace insert. This leads to a problem when you are shopping for inserts. For example, if you have a space that measures 36 inches wide by 24 inches high, you need to find the dimensions of the fireplace insert you want to buy.

You may have to look through books or on manufacturers’ websites that make inserts to get these measurements. The most common sizes are 42 by 36 inches, 48 by 30 inches, and 42 by 42 inches. If your space is bigger than 52 inches wide by 34 high, you can add a bigger size, but remember that you have to be able to fit it in the space.

When choosing an electric fireplace insert, depth is an important consideration. Standard inserts are typically 16 inches tall, but some people prefer taller units that are 18 inches deep.

Things to Consider When Measuring Electric Fireplace Insert:

How to measure an electric fireplace insert

1. Make sure the fireplace insert is acceptable for your opening and that you will be able to keep its integrity (i.e., no gaps, impediments, etc.).

2. Ensure there is a safe access space behind the electric fireplace insert once installed (at least 3 inches on all sides and rear).

3. Make sure there will be at least 3 inches of space from the bottom of your electric fireplace insert to the bottom edge of your opening.

4. Measure for a minimum clearance distance from the top of your finished floor or hearth to combustibles above (usually about 12″). Remember that you will have a visible gap between the upper back wall of the electric fireplace insert and the combustibles above.

5. Make sure you have adequate clearance for servicing your electric fireplace.

6. Measure to make sure that if you install a remote control with an emitter, it will be able to operate after installation.

7. Check for the dimensions compatibility between the product of interest, your opening, and the fireplace insert area.

8. When taking measurements for an electric fireplace insert, make sure you are not trying to fit a square (or rectangle) into a round (or oval) hole; measure for proper diameters of the product of interest versus the opening you need to fill.

Frequently Asked Questions:

Q: What Size of Electric Fireplace Do I Need?

A: An electric fireplace insert is a small enclosed space that uses an electric heat source instead of a traditional log-burning fire. They are designed to fit into existing wood-burning fireplaces and can be installed as replacements for old gas logs.

When choosing an electric fireplace, it is important to consider the size of the unit. Some key dimensions to keep in mind are the width, height, and depth of the fireplace. With these measurements, you can select the electric fireplace that will best fit your space.

An electric fireplace insert usually requires two separate measurements to find your suitable unit. Most of them are 24 inches wide, but some can be as small as 18 inches. The majority are 36 to 42 inches tall. If the fireplace has an existing opening larger than these dimensions, you can easily find your right fit without any problems.

Q: Can You Put an Electric Fireplace Insert in a Wood-burning Fireplace?

A: An electric fireplace insert must fit inside your existing fireplace. Before you purchase a unit, measure the dimensions of your existing fireplace to make sure it will work. Electric fireplaces are available in widths from about 30 inches up to 36 inches or more. Inserts can be as deep as 19 inches but check with the manufacturer for this dimension as well.

How to measure an electric fireplace insert

Measure the height of your fireplace from floor to ceiling. If you have a gas log fireplace, measure from the top logs to the bottom records. Ensure there are no less than four inches between the bottom logs if you want to use an electric insert.

Q: How Wide Does My Existing Wood-burning Fireplace Need to Be for Me to Use an Electric Fireplace Insert?

A: Measure your existing fireplace from side to side. Electric fireplaces are available in widths from about 30 inches up to 36 inches or more. If the opening is at least 32″ wide, you can expect that most electric inserts will fit.

Check with the manufacturer of the unit you want to purchase for specific measurements. Be sure to measure both the width of the unit itself (not including any projecting trim) and its projected depth.


It’s essential to know the size of your fireplace before deciding on what kind of electric insert will work best. To find out, measure the width and height of your chimney opening. This information on how to measure for electric fireplace insert can be used when determining which type of product you need and how many BTUs are required for heating purposes.

With these tips, you should be able to measure for an electric fireplace insert. If you have any additional questions or need help measuring your space, don’t hesitate to get in touch with us. We would love to hear from you and provide any support that we can!

Read On Our Another Blog – How to Close Off a Fireplace Opening

Angela Ervin

Angela is the executive editor of DIY quickly. She began her career as an interior designer before applying her strategic and creative passion to lifestyle and home. She has close to 15 years of experience in creative writing and online content strategy for housekeeping, home decorations as well as other niche efforts. She loves her job and has the privilege of working with an extraordinary team. She lives with her husband, two sons, and daughter in Petersburg. When she's not busy working she spent time with her family.

How do I know what size fireplace insert I need?

Once you have the area of the room, multiply that number by 20 to get the minimum number of BTUs you will need to efficiently heat your room. For example, a room that is 500 sq. ft. would need a fireplace insert with at least 10,000 BTUs.

How do you measure inserts?

For the Length: Start with the longest side of the insert and measure it from left to right. For the Width: At the bottom of the insert, measure from front to back. For the Height: Measure the insert from the bottom of the bendable fold down flap to the top of the flap.

Are electric fireplaces standard size?

Electric fireplaces come in many different sizes. The following three considerations can help you choose the size that will work best for your home.