Speaker Enclosure Volume Calculator
The net internal volume of a speaker enclosure is what determines how a driver tunes and performs, so it must be measured from the inside dimensions and corrected for the space that hardware occupies. This calculator multiplies the inside width, height, and depth in inches to get gross volume, then subtracts the driver, port, and bracing displacement you enter to give the net air volume in cubic inches, cubic feet, and litres. Compare the net volume to the driver manufacturer's recommended enclosure size for your chosen alignment.
Enclosure volume formula
Gross volume (cubic inches) = width * height * depth
Net volume (cubic inches) = gross - displacement
Cubic feet = cubic inches / 1,728
Litres = cubic inches * 0.0163871
1,728 is 12 cubed (cubic inches per cubic foot). The factor 0.0163871 converts cubic inches to litres exactly.
Enclosure context
- Always use inside dimensions; subtract twice the panel thickness from each outside span.
- Net volume is what the driver tunes against; gross volume is the raw cavity.
- Match net volume to the driver's recommended size from its Thiele-Small data.
- Add port-tube and bracing displacement to the driver displacement.
- Sealed and ported alignments call for different target volumes.
Enclosure volume: frequently asked questions
How do I find a speaker box internal volume?
Multiply the inside width, height, and depth (in inches) to get gross internal volume in cubic inches, then convert: divide by 1,728 for cubic feet or multiply by 0.0163871 for litres. Subtract the displacement of the driver, port, and bracing to get the net air volume the driver actually sees.
Why subtract driver and bracing displacement?
The driver basket, magnet, port tube, and internal bracing occupy space that is not available air volume. Subtracting their displacement gives the net internal volume, which is what matters for the driver's tuning and frequency response. Enter the total displacement as a user input.
What net volume does my driver need?
That depends on the driver's Thiele-Small parameters (Vas, Qts, Fs) and the alignment you want (sealed, ported, etc.). The manufacturer's recommended enclosure volume is the right target. This calculator tells you the volume your box provides; match it to the driver's spec.
Do I use inside or outside dimensions?
Inside dimensions. Subtract twice the panel thickness from each external dimension before entering, since each pair of opposing walls reduces the internal span. Using outside dimensions overstates the volume by the wall material.
How does volume affect the sound?
A larger sealed box lowers the system resonance and gives a more extended but less tight low end; a smaller box raises resonance and tightens it. Ported boxes trade volume against port tuning. Always size the net volume to the driver's intended alignment.
Official sources
- National Institute of Standards and Technology: NIST unit conversions and measurement.
- Acoustical Society of America: ASA loudspeaker and audio acoustics resources.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.