How to Measure Speaker Size

by Julien Gandelin
speaker size

Let’s face it, your factory speakers succumb to damage after a while, particularly with an immense flow of current. Resonance is one of the greatest enemies of top-notch sound, which is why you might require holding onto the sturdy housing that holds everything together and maintains high-quality music.

Determining the speaker size of your subwoofer or speaker selector will guarantee that the replacement speaker is a snug fit into the old housing. If your speakers are damaged and you’re puzzled about where to begin, you’ve come to the right place. In this guide, we’ll walk you through everything you need to know on how to measure speaker size for the perfect replacement.

A Step-by-Step Process of How to Measure Speaker Size

To get started, follow the steps below.

1. Remove the Speaker Housing

When your speakers become damaged, it evokes frustration, particularly if they don’t permit access from the back panel or front grille. When you remove the housing, you’ll need to:

  • Locate the slots at the back of the speaker panel
  • Forcefully insert two flat-head screwdrivers concurrently
  • Use a chisel to separate them if the two components are glued together. As you do, ensure you don’t damage the speaker cabinet or grille
  • Leave the foam seal intact as it curbs vibrations while forming a tight closure.

It’s worth keeping in mind that you’ll need to store the wires and screws as they’ll come in handy later. Remember to disconnect the speaker from the power outlet before you start the process, and gather the equipment required to measure the size (tape measure works well). 

2. Measure the Diameter of the Speaker


To determine the speaker’s diameter, for instance, a bookshelf speaker or tower speaker, you’ll need to measure the complete length of the speaker frame. If you’re wondering how to measure the speaker size accurately, you must identify the center which is where the diagonal, vertical, and horizontal lines intersect. To measure the diameter:

  • Begin at one hole and end at the hole located on the opposite side
  • Continue to the hole on the diagonal side
  • For an oval-shaped speaker, measure the narrow and wide side.
  • Regardless of the shape of your speaker, measure each side correctly
  • Record the respective speaker measurements.

While measuring the diameter, make sure the tape runs through the center as you hold from end to end.


3. Measure the Cutout Diameter

For the speaker replacement to be a snug fit, ensure the cutout diameter matches that of the hole in the housing. When you’re looking for a replacement for your car speaker, you must take the precise measurements as these come in a vast assortment of car speaker sizes and shapes. A wrongly sized car stereo might protrude and be susceptible to damage when you shut the car doors. To measure the cutout diameter for your car audio system, you’ll need to:

  • Put the speaker upside down
  • Measure the diameter of the widest point
  • If the speaker isn’t round, you must compute all the measurements
  • Make sure it matches the size of the hole where installation is required.

Given the absence of a standard method for measuring speakers, you must learn how to take accurate measurements.

4. Measure the Mounting Height

It’s the total distance from the top to the base of the speaker. It’s a no-brainer that speakers differ in design and shape, which is why you must identify the tallest point before you take measurements. To measure the mounting height:

  • Set the speaker in a way that the widest part is facing up
  • Measure from the bottom of the speaker, slowly making your way to the top
  • Keep in mind that the speaker must be shorter than the frame to be a snug fit
  • Make sure the speaker leaves adequate room to avoid contact with the grilles or panels.

For optimal sound quality, measure the mounting depth to allocate adequate room for installation. Typically, the speaker will surpass the mounting frame. However, if it’s overly protruding, it’s susceptible to damage once it bumps into other surfaces. Make sure your housing leaves adequate room to protect the delicate speaker after installation.

5. Measure the Diameter of the Mounting Hole

Make sure that the mounting hole matches the shape of your speaker. Therefore, you’ll need to compute the diameter of the hole from one end to another. The measurement should match the speaker’s mounting frame. Take note of whether the speaker contains a recessed lip that allows it to rest on the mounting hole. Determine the size of the recess and make sure the cutout diameter is a tad bit smaller for the perfect fit.

6. Get the Perfect Replacement

Finding a suitable replacement is no easy feat and can be crucial. A speaker with dimensions that are too big or overly small won’t fit the housing. Determine the speaker size via tracing new patterns, taking photos, or computing measurements. By doing so, you’ll avoid damage that might stem from modifications. Failure to check the measurements before investing in a new speaker means you might need to drill new holes.


Let’s discuss the answers to some of the most commonly asked questions regarding measuring speaker size.

1. What does speaker size mean?

It refers to the speaker dimension based on the diagonal distance between the mounting holes of the frame rather than the exterior diameter of the basket.

2. What voltage does a speaker use?

In the US and Canada, speakers usually have a voltage of 70 whereas, in Europe, speakers and amplifiers are typically 100V.

3. What is the best wattage for a speaker?

Anywhere between 15 watts and 30 watts is perfect for home speakers. For most homeowners, 20 watts is sufficient. Contrarily, speakers designed with large gatherings in mind have a wattage of 50 to 100 which isn’t suitable for home use.

4. How do you measure subwoofer speakers?

For starters, measure their mounting depth, diameter, mounting plate, and mounting height. You’ll discover screws around the speakers. There are usually four of them. It’s worth keeping in mind that you’ll need to determine how far the distance is between each screw and the flat diameter (the entire exterior diameter).

5. What are the varying speaker sizes?

Although speakers range from 6.5 inches to 8 inches, some users gravitate towards the larger 10-inch and 12-inch counterparts. For higher frequencies, the speaker cone must be larger than average.

6. What’s the best way to clean the speakers?

We recommend using a clean lint-free or microfiber cloth to wipe off the accumulated dirt and grime from your speakers. Nevertheless, clean gently as the last thing you need is to damage your speakers.

7. Is a lighter speaker the better option? 

None is superior to the other. It boils down to your needs and preferences. For instance, the lighter counterparts generate a high frequency. On the contrary, a heavier speaker produces a lower frequency.

8. How does a speaker work?

Once they turn the electrical signal from the amp into motion, speakers stimulate their environment. The pressurized air around the cone is what propels it. The cone moves backward to rarefy the air. Resultantly, these pressure waves broaden from the speaker and your ears absorb the pressure changes as sounds.

9. Are there other factors to consider when measuring the speaker size?

  • The Weight of the Speakers 

Speakers vary in weight from one type to another. For instance, the weight of car speakers is based on where they’ll be installed, which is why lightweight counterparts that are a snug fit in door panels are the better option.

  • The Type of Screw Mounting

The mounting screw and new speaker such as a bookshelf speaker must be a match with the old one when it comes to size and shape. Therefore, the screw comes in handy to easily twist the nails into their respective screw holes. You don’t need to drill new holes to match the new types of screws.


Armed with the knowledge of how to measure speaker size, finding the ideal replacement is easier. You don’t need to worry about the new replacement being overly big or too small.


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