Enter the box’s external dimensions and wall thickness to get the real net internal airspace — the number that actually matters against your subwoofer’s spec.
Net internal airspace
—
How this is calculated
Internal dimension = external dimension minus twice the wall thickness (material on both sides). Multiply the three internal dimensions for internal volume in cubic inches, divide by 1728 to get cubic feet, then subtract driver and bracing displacement if you have that number from the subwoofer's spec sheet.
This is plain geometry — it doesn't account for port volume on a ported box, rounded internal corners, or irregular bracing. For a precise build, we account for those directly; this calculator is for a fast sanity check before you order.
What to do with the result
Compare the result to your subwoofer's recommended sealed (or ported) volume range from its spec sheet. If the box you're checking is well outside that range, it's the wrong box for that subwoofer, regardless of whether it physically fits your vehicle.
Not sure what your subwoofer's recommended volume is? Contact us with the model number and we'll look it up.
