Practical tools for measured work
Speaker Box Volume & Cut List Calculator
Calculate gross and net internal enclosure volume, a six-panel cut list and an estimated port length.
Enter the total volume occupied inside the finished cavity.
Port length is a compact single-round-port estimate using one internal-radius and 0.6 external-radius end correction. Confirm fit and refine the port in the dedicated port calculator.
How it works
Direct answer. Enter finished outside dimensions, panel thickness and the volume occupied by the driver, braces and port. The calculator returns gross cavity volume, usable net volume, a six-panel cut list and a compact round-port length estimate.
Method. Each internal dimension equals the outside dimension minus twice the panel thickness. Gross volume is internal width x height x depth; net volume subtracts entered displacement. The port summary uses the lumped Helmholtz relationship with the displayed net volume.
Worked example. A 400 x 500 x 350 mm shell in 18 mm material has a 364 x 464 x 314 mm cavity, or about 53.0 L gross. Subtracting 5 L of occupied volume leaves about 48.0 L net.
Cut convention. Front and back cover the full face. Sides fit between front and back; top and bottom fit between those panels and the sides. Change the dimensions if your joinery stacks differently.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Units
- Millimetres / litres
- Outside width
- 400
- Outside height
- 500
- Outside depth
- 350
- Panel thickness
- 18
- Driver, brace and port displacement
- 5
- Port summary
- Ported: estimate one round port
- Single round port inside diameter
- 100
- Target port tuning
- 35 Hz
Primary result: Net internal volume: 48.03 L.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
This is a rigid rectangular-box planning model, not a complete loudspeaker simulation. It does not predict driver response, leakage, damping, panel resonance, port losses or chuffing. Manufacturer displacement and electro-acoustic driver data govern the final design. The cut list excludes kerf, rebates, dados, double baffles, tolerance and finishing allowance.
Frequently asked questions
What belongs in displacement?
Add the manufacturer's driver displacement plus the measured or modeled space occupied by braces, ports, amplifiers and other internal parts.
Why can the port result say not feasible?
For some combinations, the requested tuning would require an effective port shorter than the assumed end correction. The box volume is still useful, but the port geometry must change.
Is this sealed or ported box volume?
The volume and cut list apply to either rigid rectangular shell. The optional port summary is only a starting estimate for a vented enclosure.
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