Your result
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Enter your values, then click Calculate result.How this calculator helps
This subwoofer case calculator estimates the air volume inside a rectangular six-panel enclosure. Enter external width, height and depth in inches, uniform panel thickness and the total displacement of drivers, braces and any ports inside the box. The outputs separate gross internal volume from net air volume and convert the latter to litres. This is geometry, not an acoustic design model: it does not choose a driver, calculate port tuning or decide whether the enclosure matches a manufacturer’s required volume.
How to use it
- 1
Read the labeled input units and select the supported calculation mode where available.
- 2
Enter the values established from the source records described below; do not substitute a different measurement basis.
- 3
Click Calculate result to calculate from the supplied inputs.
- 4
Read the main output together with the checks and limitations. After editing inputs, click Calculate again to update the stored result.
Formula and methodology
Internal dimension = external dimension −2×panel thickness. Gross ft³ = internal width ×height ×depth/1,728. Net ft³ = gross ft³ −supplied displacement. Litres = net ft³ ×28.316846592.
The calculator applies the displayed arithmetic to the values entered on this device. It does not silently load a local tax rate, currency conversion or commercial assumption.
Worked calculation example
External dimensions 16×16×16 in with 0.75 in uniform panels give 14.5 in internal dimensions and 1.7642505787 ft³ gross. Subtracting 0.1 ft³ displacement gives 1.6642505787 ft³ net, approximately 47.126328 litres.
How to interpret your result
The net result is remaining air space under the supplied rectangular construction assumptions. It is useful for checking a takeoff but cannot choose an enclosure alignment or validate a driver specification. The gross output and internal dimensions expose the subtraction steps so you can detect an external-versus-internal measurement mix-up.
For different inputs or formulas, use Volume Calculator; Cubic Yard Calculator; Linear Feet Calculator.
Related questions this calculator covers
- subwoofer case calculator
Scenario comparison
| Scenario | What it shows |
|---|---|
| 16-inch cube with 0.75-inch panels | 14.5-inch internal cube. |
| Zero displacement | net and gross volume are equal. |
| Displacement equal to gross volume | no positive-air-space result is accepted. |
Common mistakes to avoid
- Entering interior measurements as external dimensions.
- Using nominal driver diameter as driver displacement.
- Treating a volume calculation as a complete acoustic design.
Measure or calculate the three actual interior dimensions, multiply them and divide by 1,728 for cubic feet. Subtract each documented displacement exactly once. Compare the remaining volume with the manufacturer’s stated net or gross basis, without assuming volume alone validates the enclosure design.
Authoritative reference. JL Audio manufacturer instructions hosted by Garmin distinguish recommended net enclosure volume and displacement. No model-specific target is loaded by SolvePilot.What can affect the result?
External dimensions are not the internal air space
Wood or other panels occupy part of every external dimension. Under the stated uniform six-panel model, twice the panel thickness is subtracted from width, height and depth. Entering internal dimensions in those fields would subtract thickness again and understate volume. Conversely, multiplying external dimensions directly would overstate the available air space. Real builds with double baffles, unusual joinery or nonuniform panels need a takeoff matching their actual interior geometry rather than this simplified rectangular assumption.
Account for objects occupying the interior
The driver basket and magnet, braces and internal port structures displace air. Sum the relevant displacement on a consistent cubic-foot basis and enter it once. Use manufacturer data or an independently measured geometry rather than guessing from the nominal driver diameter. The field is a total, not a per-driver amount. If you use several drivers, include their combined displacement and any shared braces. A displacement at or above gross internal volume is rejected because no positive modeled air space remains.
Gross and net volume must stay distinct
Gross internal volume describes the interior before subtracting the supplied objects. Net volume describes the remaining modeled air space. Manufacturer recommendations can specify one or the other, so read the selected driver’s documentation carefully. The worksheet does not load a target or decide which recommendation applies. A number that matches a recommended net volume is not by itself proof that the enclosure construction, port arrangement or driver use is suitable.
Volume alone cannot determine acoustic behavior
A subwoofer system’s response depends on the driver, enclosure type, leakage, damping, electrical arrangement and other design information. This page supplies no frequency response, impedance, port length, tuning frequency or power-handling prediction. A ported box is not correctly designed simply by subtracting a port displacement from a rectangular volume. Use the manufacturer’s full design guidance or a validated acoustic model for that task. Keep the geometry result separate from a claim about sound quality or safe operating power.
Validate dimensions and report appropriate precision
Every external dimension must exceed twice the panel thickness, and thickness must be positive. The browser rejects impossible geometry instead of producing a negative volume. A tape measurement’s precision determines the practical confidence in the result; long decimal outputs do not imply the built box has that exact capacity. Check internal dimensions independently after assembly if necessary. The computation is local and does not upload a drawing or access a manufacturer catalog when you click Calculate result.
Privacy and browser processing
Values entered on this page are processed in the current browser session. SolvePilot does not require an account and does not receive the values entered into the calculator. Refreshing or closing the page clears the working values unless the browser itself restores a previous session. Avoid entering identifying or account information because the calculation needs summary values only.
Accuracy and verification
Accuracy depends first on input quality. Confirm definitions, scales, dates and source information before entering a value. Keep an independent record of any result used for planning because this page does not create an official statement or retain a calculation history.
Limits of this estimate
The net result is remaining air space under the supplied rectangular construction assumptions. It is useful for checking a takeoff but cannot choose an enclosure alignment or validate a driver specification. The gross output and internal dimensions expose the subtraction steps so you can detect an external-versus-internal measurement mix-up. Every external dimension must exceed twice the panel thickness, and thickness must be positive. The browser rejects impossible geometry instead of producing a negative volume. A tape measurement’s precision determines the practical confidence in the result; long decimal outputs do not imply the built box has that exact capacity. Check internal dimensions independently after assembly if necessary. The computation is local and does not upload a drawing or access a manufacturer catalog when you click Calculate result.
Sources and review information
Frequently asked questions
Should I enter internal or external dimensions?＋
Enter external rectangular dimensions. The calculator subtracts twice the uniform panel thickness in each direction.
What belongs in displacement?＋
The combined internal volume occupied by the drivers, braces and any ports or other structures, on the same cubic-foot basis.
Does it design a ported enclosure?＋
No. It calculates geometric volume only and supplies no acoustic tuning or port-length model.
Why are gross and net results different?＋
Net volume subtracts the supplied displacement from gross internal space. The product specification controls which basis you need.
Can I use a double front baffle?＋
This uniform-panel model does not separately represent a double baffle. Use actual interior geometry or an appropriate more detailed model.