How to Measure a Subwoofer

How to Measure a Subwoofer? Easiest Way To Do It

So your current subwoofer went out or you’re planning to upgrade to a new model? In that case, you’d want to save some cash by using the existing enclosure instead of buying a new one.

This brings in the need to measure the subwoofer. You want to know the exact measurements of your old speaker so that you can replace it with a model of the same size that easily fits in the excising enclosure.

Read on to discover how to measure a subwoofer correctly…

What Exactly Should You Measure?

The physical size is one of the most important considerations to make when replacing your old car subwoofer with a new one.

The market has multiple subs with varying sizes, so taking these measurements is crucial to ensure you get a perfect replacement.


you don’t want to invest in that latest subwoofer under 1000 and then get disappointed and frustrated when you get down to mounting it and discover it just won’t fit where the old speaker was mounted in your car.

That said, the physical size is determined using the excising speaker’s diameter, mounting height, and mounting depth.

  • Speaker diameter: refers to the measurement of the outside diameter of speaker frame, with the exclusion of any mounting lugs present. Getting the right diameter for the old speaker enables you to find a new speaker with the same size as the old, so it can comfortably fit in the mounting space for your old model.
  • Cutout diameter: refers to the measurement of mounting hole size required for the surround and cone to clear the speaker’s mounting plane.
  • Mounting height: this measurement indicates how far the speaker’s front-most part projects from the front mounting plane. this measurement is important as it helps ensure your new speaker doesn’t stay too high, to the point of bumping against your door panel or factory grill.
  • Mounting depth: a measurement of how the speaker’s rear-most part projects from the front mounting plane. this will help ensure the speaker doesn’t go too deep and start bumping against any obstructions below it.

Here’s a diagram illustrating the various measurements you need to take when measuring a subwoofer…


Photo: Crutchfield

How To Measure Your Existing Subwoofer:

Step 1: Remove the subwoofer from its enclosure.

The first step involves turning off your sub and removing it from its enclosure or mounting. You might need a screwdriver to remove the mounting holes if your speaker is an enclosure.

Be sure to remove any covers in front of your speaker as well for easy measuring process.

Once you pull out the speaker from its mounting, disconnect any wires attached to it so that it’s completely detached from the enclosure.

Step 2: Measure the speaker mounting depth.

With the speaker sitting upright, take a ruler or tape measure and use it to measure the mounting depth of your sub—i.e., the height from the back of your speaker to its mounting frame.

Start measuring from the bottom up to the flat metallic or plastic piece around the cone (the mounting frame). Note down the resulting measurement as the subwoofer’s mounting depth.

Step 3: Now measure the mounting height.

Now, you’ll need to take the distance from the bottom of your speaker mounting frame all the way up to its highest projection point.

Measure a Subwoofer

With the speaker sitting upright, place your ruler or tape measure at the bottom of the mounting flange and find the height from this plate to the highest point of the speaker.

You can look at your speaker from the side to get a clear picture of how far it protrudes from the mounting plate.

Ensure you note down this height on a paper as the mounting height.

Step 4: Take the cutout diameter measurement.

flip your speaker upside down and measure the distance from the widest point of your speaker cone attached to the back of the speaker mounting plate (see the illustrated image above).

If your speaker doesn’t have a round shape, then consider measuring the widest point from each side so that you know each dimension.

Note down the resulting measurement as cut-out diameter.

Step 5: Measure the mounting screw width.

The last measurement you need to take is the distance between the screw holes on your speaker mounting frame.

however, this measurement might not be important as the other we’ve described above as you can always drill new holes to hold your new speaker.

Final Verdict

That’s how you obtain the essential measurements of a subwoofer, from the speaker cutout diameter to the mounting height, mounting depth, and even the mounting screw width.

When you take these measurements, note them down on a piece of paper and compare them against the specs of the new speaker you plan to buy. This will help ensure that that best powered subwoofer for cars you purchase perfectly fits in your car.

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