How to Calculate the Box for a Subwoofer

By Nichole Liandi

Your subwoofer needs the right size box.
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When building a subwoofer box, you'll need to do a little math before you begin cutting wood. Each subwoofer is designed to operate in a specific volume of enclosure. For your sub and sub box to sound good, match the size of the enclosure to that spec.

Step 1

Search for the box volume requirements for the subwoofer you're building the box for. Manufacturers of subwoofers list this specification in the manual or on their website. The volume of the box is usually listed in cubic feet.

Step 2

Sketch out several possible box dimensions and check the volume of the box design. The simplest box design is a cube. To determine the volume of a cube in cubic feet, measure the width, height, and depth in inches, multiply the three numbers together, and divide the resulting number by 1,728. For example, a box that measures 12 inches by 12 inches by 12 inches has a volume of 1.0 cubic feet; 12 x 12 x 12 = 1,728.

Step 3

Decide on the dimensions for your subwoofer box's front panel. This is an important step because the front panel will hold the subwoofer. You'll want the panel to be large enough to hold the sub with sufficient room to construct the box around the clearances of the sub. A good rule of thumb is to add at least 2 to 3 inches to the size of the subwoofer. For example, a 10-inch sub should have a front panel at least 12 to 13 inches square.

Step 4

Size the depth of the box to create the volume you require for your box. Make the box's design deep enough so that the subwoofer has sufficient mounting room.