🔊 Speaker Box Calculator
Estimate the internal air volume of a rectangular speaker box from its outer dimensions and material thickness.
What this calculator does
When building a speaker or subwoofer enclosure, the internal air volume matters more than the outer dimensions because it directly affects the driver’s bass response. This calculator converts external box dimensions and panel thickness into the true internal volume.
The formula
The internal (gross) dimensions equal the external dimensions minus twice the panel thickness on each axis, since thickness is lost from both sides of each dimension. Multiplying internal width by height by depth gives the gross volume, which is then converted from cubic inches to liters (1 liter = 61.024 cubic inches). Finally, subtracting the volume displaced by the driver magnet, bracing, and port gives the usable net volume, which is what matters for matching a driver’s recommended enclosure specification.
This tool provides a general estimate for planning purposes. For precise tuning, consult your driver’s specification sheet and account for port volume separately if building a ported box.