Speaker Box Volume Calculator
Calculate speaker enclosure volume from internal dimensions, minus driver displacement, plus ported-box port length.
Processed locally in your browser — nothing is uploaded.
Speaker Box Volume Calculator
Volume the driver (and bracing) occupies inside — on the driver spec sheet.
Results
- Gross internal volume
- 70 L
- Net volume (after driver)
- 69 L
- Net volume (cubic feet)
- 2.437 ft³
Measure internal dimensions (outer dimensions minus twice the wall thickness). Compare the net volume with the driver's recommended sealed enclosure range (Vas/Qts based).
About Speaker Box Volume Calculator
Sealed mode multiplies the internal dimensions and subtracts the driver's displacement to give net volume in liters and cubic feet. Ported mode adds the required port length for a target tuning frequency using the standard Helmholtz round-port formula Lv = 23562.5·D²·Np ÷ (Fb²·Vb) − 0.732·D.
Common uses
- Check a subwoofer box design against the driver's recommended volume
- Find the port length to tune a build to 32 Hz
- See how a bigger port diameter changes the required length
Example
Input
50 L net box · 10 cm port · 35 Hz target
Output
≈ 31.1 cm port length
Limitations
- The port itself displaces volume and slightly detunes the box — subtract it and iterate for precise builds. Flared ports and slot ports need adjusted end corrections.
Frequently asked questions
How do I calculate speaker box volume?
Multiply the internal length, width, and height (interior dimensions, inside the walls), then subtract the volume the driver itself occupies. In centimeters that product divided by 1000 gives liters, and one cubic foot is about 28.32 liters.
How does a ported speaker box actually work?
The air in the port acts as a mass bouncing on the springiness of the air sealed in the box — a Helmholtz resonator. Near the tuning frequency the port's output reinforces the driver, extending bass response below what the same sealed box manages.
How does port diameter affect the required port length?
Length grows with the square of diameter in the tuning formula, so a wider port needs a considerably longer tube to hit the same frequency. Wider ports resist audible air noise (chuffing) at high output, which is why builders accept the extra length.
Are my speaker design dimensions saved on a server?
No. The volume and port-length math runs in your browser and none of your box dimensions or tuning targets are uploaded or stored.
Should I subtract the port volume from the box volume?
Yes, for precise builds — the port tube displaces air inside the enclosure just like the driver does, which slightly detunes the box. Subtract the port's volume from the net figure and recalculate the length once or twice until it converges.