How to Calculate a Subwoofer Box
A subwoofer in your car can really improve the overall sound of your system. While you can buy subwoofers already installed in pre-made boxes or buy off-the-shelf boxes and mount a subwoofer into them, you may have a desire or need to build your own subwoofer box. Since subs are designed to operate properly in very specific enclosure sizes, it's necessary for your box to match the needs of the subwoofer. You'll need to do a few calculations when designing a subwoofer box.
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Instructions
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1
Determine the optimal enclosure size for your subwoofer. Subwoofer manufacturers will publish this specification for their subs in the manual that comes with the subwoofer. Additionally, you can usually find this spec on their websites. This specification will be listed in cubic feet.
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2
Sketch out some designs that will fit in the space you have available for your box. A cube design is the simplest to calculate.
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3
Multiply together the width, height and depth dimensions (in inches) of your projected box. To be accurate, use the internal dimensions of the box, keeping in mind the thickness of the wood you'll be using in the box's construction.
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4
Take the number you came up with in Step 3 and divide it by 1,728. Why 1,728? Imagine a box that's 12 inches by 12 inches by 12 inches. Because it's one foot in all dimensions, the box is one cubic foot in volume. Multiply 12 x 12 x 12 and divide by 1,728. The answer is 1, for 1 cubic foot.
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5
Check to see if the answer you came up with in Step 4 matches the specified volume of your subwoofer. If it doesn't, modify the dimensions of your enclosure and recalculate until you come up with a design that meets your needs.
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Tips & Warnings
For more complex subwoofer box shapes than a simple cube, use the box calculator listed in Resources below.
