BoxwrightCar audio and DIY speaker boxes
Design the box. Then build that box.
Pick your sub, get the net volume and the port, and a cut list that already counts the port walls and the baffle. When it is built, play a slow tone sweep and see where your box really tunes.
- No account
- No subscription
- Works offline
- Net volume
- 1.75 ft³
- Tuning
- 34 Hz
- Port
- 4″ × 13.7 in
- Input check
- ✓ all clear
Free tools on this site
The same formulas as the app, in your browser. No sign-up, nothing to install.
- Box calculatorSealed Qtc, Fc and F3, or the port length for a ported box.
- Datasheet checkTest Qts, Fs, Vas, Sd and Bl against each other, and catch unit mix-ups.
- Wiring chartsFinal impedance for 1 to 4 subs, SVC and DVC, series and parallel.
- Port tuning checkFind where your built box really tunes, then cut the port to fix it.
- ValidationReference vectors, the Hornresp comparison, published values and our tolerances.
What the app does
Box, port and net volume together
Change the port and the net volume follows. Port walls, the driver, bracing and a double baffle come off the gross volume before the tuning is worked out.
Checks the datasheet first
Qts, Fs, Vas and Sd are tested against each other. A Vas typed in cubic feet as litres, or an Sd in cm², gets caught before you cut wood.
A verdict for the car
Enter your amp’s real RMS. You get one of three answers: fine, port noise likely, or over Xmax, with the box size or subsonic filter that fixes it.
Fit to space, then a cut list
Give two outside sizes and the net volume, get the third. Then a cut list in 1/16 inch or mm, with saw kerf, baffle, port walls and the driver hole.
Check my box
A slow tone sweep through your amp. Where the cone nearly stops, that is the real tuning. Then it tells you how much port to cut off.
Build card
One image with the driver, net volume, tuning, port and F3 to post on a forum, plus a project file another phone opens with every number.
Free, for good
- Unlimited boxes and your own drivers
- About 700 drivers from manufacturer datasheets
- Input check, sealed and ported design
- Port and net-volume ledger, fit to space
- Cut list for square and wedge boxes
- Wiring for 1 to 16 subs, port noise and Xmax warnings
- Check my box, build card, backup
Pro, one payment
- SPL, cone travel, port speed and group delay curves at your power
- Cabin gain, and sealed against ported on one chart
- 4th-order bandpass design
- Sheet layout: how many sheets, and where each part goes
- PDF build sheet for the shop
- Every alignment side by side
Try Pro free for 7 days, once. It never turns into a payment by itself. When the trial ends your boxes stay as they are.
Your boxes stay on your phone
No account, no server, no analytics. Boxwright asks for no permissions at all. The tone check only plays sound; it never uses the microphone. The only network traffic is the store, when you buy Pro.
Numbers you can check
Every result shows the formula and your numbers. The maths runs against 338 worked examples, 79 of them published values from datasheets and papers, and against Hornresp on 7 real designs.