Design speaker boxes with gross and net airspace. Include thickness, ports, bracing, and driver displacement. Review results instantly and export practical planning documents easily.
| Example | Shape | Outer Dimensions | Wall | Driver Data | Gross Internal | Net Internal |
|---|---|---|---|---|---|---|
| 1 | Rectangular | 60 × 40 × 35 cm | 1.8 cm | 1 driver, 1.5 L, 0.8 L bracing, 0.2 L terminal | 64.463 L | 61.963 L |
| 2 | Wedge | 75 × 38 × 24/34 cm | 1.8 cm | 1 driver, 1.4 L, 0.9 L bracing, 0.2 L terminal | 62.386 L | 59.886 L |
| 3 | Cylindrical | 40 cm diameter × 55 cm length | 1.2 cm | 1 driver, 1.1 L, 0.4 L bracing, 0.1 L terminal | 58.405 L | 56.805 L |
Rectangular gross internal volume: V = Width × Height × Depth
Wedge gross internal volume: V = Width × Height × ((Top Depth + Bottom Depth) ÷ 2)
Cylindrical gross internal volume: V = π × Radius² × Length
Internal dimensions: Internal size = External size − 2 × wall thickness
Total displacement: Drivers + bracing + terminal cup + port displacement
Net internal volume: Gross internal volume − total displacement
Round port displacement: V = π × Radius² × Length × quantity
Slot port displacement: V = Width × Height × Length × quantity
Estimated port tuning: This page uses a Helmholtz style approximation with total port area, effective length, and acoustic box volume.
Dimensions are converted to centimeters internally. Final volume is reported in liters and cubic feet for quick enclosure planning.
Speaker boxes work with air like springs. The real working volume is the air left after subtracting drivers, ports, bracing, and terminal cups. That remaining space strongly affects low frequency behavior, transient response, and efficiency.
Many builders start with outside measurements only. That is useful for cutting panels, but it does not reveal the actual acoustic airspace. Panel thickness reduces every inside dimension. A larger wall thickness can remove more airspace than expected.
A woofer basket, motor structure, shelf brace, or long vent each takes volume. Ignoring those items makes the design appear larger than it really is. The final enclosure may then miss the target alignment and sound different from the plan.
Ported boxes add another design layer. The port occupies space and also changes box tuning. A long port can remove several liters in compact builds. This page estimates tuning frequency from box air volume, port area, and effective port length.
Rectangular enclosures are common and easy to cut. Wedge boxes fit vehicle seats and angled spaces. Cylindrical tubes can reduce standing panels and save space in custom installs. The best shape depends on room, material, and installation goals.
Manufacturers often publish recommended internal volume in liters or cubic feet. This calculator shows both values so you can compare your result directly with a speaker specification sheet without performing extra conversion work.
Use the result block to compare box ideas before cutting wood. Small dimension changes can shift net volume quickly. Exported tables and PDFs make it easier to share a design with clients, installers, or your own workshop notes.
Net internal volume matters most. It represents the actual airspace after subtracting drivers, ports, bracing, and terminal hardware. That value affects enclosure behavior more than outside size.
Enter outer dimensions in this page. The calculator subtracts wall thickness to estimate the internal size. That approach helps builders who start with cut panels or cabinet sketches.
Speaker baskets and motor assemblies take physical space inside the box. If you ignore that space, the real air volume becomes smaller than planned and performance may shift.
Yes. The unit selector supports millimeters, centimeters, and inches. The calculator converts those dimensions internally, then reports volumes in liters and cubic feet.
Yes. Use no port for sealed designs. Use round or slot port options for vented designs. The page also estimates port tuning when enough port data is provided.
That means the box is too small after subtracting displacement. Increase the enclosure size, reduce wall thickness where appropriate, or use components that consume less internal volume.
No. It is an engineering estimate based on common vented-box physics. Final tuning can still change with flare geometry, stuffing, end corrections, and construction details.
Yes. The result block includes CSV and PDF export options. Those downloads are useful for shop records, quotations, design reviews, and installation planning.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.