How to Measure Car Speakers Size?




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When replacing car speakers, you want to make sure that new speakers have the correct size and will fit in your car.

Most of the speakers have their dimensions written down. However, when this information is missing, you must measure the existing speakers. But how to measure car speakers to ensure they will fit the car? Let’s find out.

To measure the speakers’ size, set the speaker upright, so the widest part of the cone is facing up. Then, use a ruler or tape and measure at the widest point of the speaker from one edge of the mounting frame to the other. If the speakers are not circular but oval, take several measurements around the speakers.

Tip: Measure all speakers’ dimensions is not too complicated, but it should be done using precise measure tape or a good quality ruler.

I use a transparent ruler, which is especially handy when measuring the screw mounting holes.

However, for measuring depth or speakers’ height, I found it better to use a metal measure tape. My favorite is a CRAFTSMAN tape with a self-lock mechanism.

In the article below, I will go through all critical dimensions that define whether specific speakers will fit into your car. 

What Dimensions Are Important For Car Speakers?

When looking at the car speakers, you see at least a dozen different sizes within all shapes. Although all of them are critical from the speakers’ design side, not all are important when thinking about installing them in the car.

Mounting Depth

Mounting depth tells you how much room we need behind a speaker to ensure no contact between the magnet and door panel or any other objects after installation.

When speakers are too deep, you may have a problem with either installation as a whole or with the blocked movement of the door windows.

Mounting Height

Mounting height tells you how far the speaker’s front sticks out of the door panel after installation.

This dimension is critical, especially in the coaxial speakers with tweeters higher than the speaker’s surroundings being mounted behind the door panels.

If you install car speakers behind door panels without original grills, it is worth ensuring there is enough free space in front of the cone after mounting.

Cutout Diameter

The cutout diameter of the car speakers directly affects its position inside the mounting hole. Although the speaker should fit nicely in the hole, there is no room for a tight fit.

It is better to have a cutout diameter slightly smaller than the mounting hole rather than too tight.

A tight fit can cause installation problems and increase the risk of damaging the speaker’s basket. In worse cases, a weaker speaker’s basket can be distorted and damaged.

Mounting Screws Diameter

The diameter of the mounting screws is essential if you want to ensure a stable speaker location in the mounting hole.

There are slight differences between similar car speakers, even if they are theoretically the same. For example, 6.5″ is not always precisely 6.5″. It is, therefore, crucial to know the exact dimension.

In case of differences, you can mount the speaker that will end up being in the offset, or when placing it on top of the MDF distance rings, you can have one of the screws outside of the ring’s outer diameter.

Noteworthy is also the number of mounting holes you want to measure. For example, when a car speaker has four mounting holes, the measurement of these dimensions is straightforward, and the only thing you have to do is measure two holes that are across from each other.

More complicated is a measurement taken from car speaker with three mounting holes. In this case, handy will be the speakers’ factory specifications and compare it with the speaker we want to purchase.

In some cases, however, installing the speakers on the distance rings will automatically change the number of mounting holes to match the new ones.

how to measure car speakers

Measuring Car Speakers Screw Pattern

Screw pattern is the easiest dimension to be measured with no difference for the round, oval, or square speakers. Use a tape measure or a ruler to measure it correctly, and take your measurements for the car speaker holes across from each other.

The more difficult it is to measure the screw pattern in the speakers with a nonsymmetrical shape or uneven mounting holes.

However, these are specific cases, and when replacing such speakers, it is better to use adaptor rings fitting the original location in the car.

Conventional sized aftermarket speakers have a wide choice of different models to choose from, so you can select a speaker to fit your needs.

measuring mounting screws diameter in car speakers

How Do You Measure Speakers Cutout Diameter?

To measure car speakers cutout diameter, flip the speaker upside down so the magnet is on the top of the speaker.

The cutout diameter is the widest part of the cone attached to the back of the speaker basket. The right way to measure it is to use the ruler and look from the top of the magnet down.

However, using a ruler may not be the most accurate. More accurate results you will have when using large vernier, which jaws will cover both sides in the widest point of the speaker.

If your speaker is not round, measure the widest point from each direction. Remember that the cutout diameter must be smaller than the mounting hole in which the speaker will be installed.

measuring speaker cutout diameter

How to Measure Car Speakers Mounting Depth?

When you are wondering how to measure car speakers mounting depth, do not worry. This is actually the simplest measurement you can make. To find the mounting depth, you must flip the speaker again and place it on a flat magnet surface with a cone facing up.

When the speaker lies on its magnet, measure the distance between the flat bottom surface and the bottom of the mounting frame.

Make sure your new car speakers are not higher than measured factory speakers, otherwise you may have problems when mounting them, or it may cause speakers to damage when the magnet touches other metal car elements.

measuring mounting depth in car speakers

How to Measure Speakers Mounting Height?

To measure car speaker mounting height, place the speaker with the cone facing up.

The height of the speaker that stays above the mounting area can be measured using two rulers. Place one ruler horizontally on top of either speaker surrounding or the tweeter in coaxial speakers, ensuring a parallel position against the mounting area.

Place the second ruler in a vertical position across the top ruler and bottom of the mounting frame. The measurement you take is the distance between both surfaces.

When buying new speakers, make sure they are not too tall, which could cause damage when in contact with other objects, like plastic door panels.

How to Measure Mounting Holes in Car Speakers?

The only tool you will need to measure the mounting hole outer diameter is the ruler.

Look at the shape of the hole and determine the widest area. If the hole is round, place a ruler across the mounting hole. For mounting holes with different shapes than round ones, you have to check the widest and smallest diameter and measure both.

Remember that the mounting hole should be slightly bigger than your speaker’s cut-off diameter. Otherwise, the car speaker will not fit freely.

How to Measure Depth of the Speaker Mounting Hole?

Mounting hole depth is critical to fit the speaker without the risk of the magnet’s contact with the interior door panel.

To measure it right, place the ruler inside the mounting hole and push it as far back as it can go, and check the value.

When measuring depth, you have to check several points across the diameter and in the center of the hole if the bottom surface of the mounting hole is uneven.

When you have several different measurements from the various points, your maximum depth is the smallest value you have found.

When buying new speakers, make sure their depth is smaller than the minimum measured depth of the mounting hole. Otherwise, the speaker will not sit flat on the mounting surface, or installation may not be possible at all.

How to Measure Car Subwoofer?

Measuring the dimensions of a car subwoofer can be done in a few different ways, depending on the specific information you need to gather. 

Here are a few methods you can use to measure the dimensions of your subwoofer:

#1. Physical Measurement

This method involves physically measuring the subwoofer using a tape measure or ruler.

You can measure the diameter of the subwoofer’s frame, the depth of the subwoofer’s cone, and the height of the subwoofer’s surround.

#2. Use the Manufacturer’s Specifications

Many manufacturers will provide detailed specifications for their subwoofers, including the dimensions.

This information is usually available on the manufacturer’s website or the subwoofer’s manual, often together with the subwoofer’s detailed drawing. 

#3. Use a Digital Caliper

A digital caliper is a precision measuring tool that you can use to measure the subwoofer’s dimensions with high accuracy.

#4. Use a 3D Scanner

A 3D scanner can create a digital model of the subwoofer, which can then be used to measure the dimensions. This is however more of an industrial solution often used to design customized enclosures.

Can I Use Different Speaker Sizes in My Car?

You can use different speaker sizes in your car.

In fact, many car audio systems include a variety of speaker sizes to provide a balanced and full sound.

Here are a few key points to consider when selecting speaker sizes for your car:

#1. Speaker Size and Power Handling:

The size of the speakers you choose will affect the power handling capability of your system.

Larger speakers can typically handle more power than smaller ones, so consider the power output of your amplifier or car stereo when selecting speakers.

#2. Frequency Response

The size of the speaker also affects the frequency response, especially for the bass speakers.

Speakers with larger cones tend to have a more balanced frequency response, while smaller speakers may not be able to produce as much bass.

#3. Soundstage and Imaging

The size and placement of the speakers can also affect the soundstage and imaging of your system, but this is more related to the coaxial speakers with adjustable tweeters.

Nevertheless, speakers with larger cones can create a wider soundstage, while smaller speakers may provide a more focused and accurate image.

#4. Installation

Some car models have limited space for speakers and may require smaller size speakers to fit.

To ensure a proper fit, measure the size of your car’s speaker mounting holes and compare them to the size of the speakers you’re considering.

Why Car Speakers Have Different Sizes?

Although the manufacturers use standardized sizes, the actual differences between the speakers, even within the same range, which are not higher than a fraction of an inch, or a few millimeters, can disqualify some speakers from mounting them in your car.

Many 6.5″ are not exactly 6.5″, or 6×9″ are not 6.9″. That is why knowing which speaker dimensions are important, and you need to know this before purchasing and installing them in your car.

The last thing you want is to install hi-end car speakers that make the perfect sounds you need and to find out that it is too deep so you cannot open a window.


When researching the speakers, you need to know several measurements and the manufacturer’s information to determine if the speakers will fit in the car.

The size designation is closely related to their frame’s diagonal measurement and hole alignment. So it’s not just about the diameter of the speaker’s cone or the cutout diameter, which is a common misunderstanding.

Determining the size of the factory speaker in your vehicle can be tricky. These speakers do not always match the aftermarket speakers’ standards because the factory speakers are designed to work with a specific vehicle and have unusual height or magnet depth.

The easiest way to replace car speakers is to buy their direct factory replacement. However, it does not make much sense since we want to improve car audio sound quality and not just replace speakers.


How to Measure Car Speakers Size?

When measuring the size of car speakers, the most important measurements to take are the diameter of the speaker’s frame (also known as the “basket”) and the depth of the speaker.

To measure the diameter, simply measure the distance across the speaker from one outer edge to the other.

To measure the depth, take the distance from the front of the speaker’s frame to the back of the speaker.

What Are the Standard Speaker Sizes for Car Stereo Systems?

The standard speaker sizes for car stereo systems are circle 6.5″, 5.25″, and 4″, and oval 6×9″ or 5X7″.

These sizes can vary depending on the make and model of the car. Therefore, it’s important to check the specifications for your specific vehicle to ensure you are purchasing the correct size speakers.