Accurate calculation of enclosure volume for your subwoofer box is essential in designing a properly functioning subwoofer. This calculator will calculate the volume for a square or rectangular shaped sealed subwoofer enclosure and requires the use of decimals (.25, .50, .75 etc.). For a square or rectangular subwoofer enclosure, the calculation for net volume is (width x height x depth) Enter your desired box dimensions and material thickness to calculate your internal volume NOT including speaker displacement.