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How to build a subwoofer box

This DIY project can be a real money-saver

Erin Blanton wrote about mobile A/V gear at Crutchfield for several years, and worked as a Sales Advisor in our contact center before that. She left Crutchfield to open her own toy store, Pufferbellies, in nearby Staunton, Virginia, which continues to keep her busy.

More from Erin Blanton

Custom box


Building your own subwoofer box is a great way to get the look and fit you want, without spending a fortune. All you need is a few basic tools, hardware, and materials.

We'll explain how to design your subwoofer box on paper. Getting the math right is crucial for getting the proper volume. 

Next, we'll walk though a build, step by step, and share a few tips along the way. 

Building a box is a lot of fun and will save you some cash, but DIY jobs aren't for everyone. If you get through this article and decide that box building might not be for you, then check out our selection of high-quality, premade subwoofer boxes

Cost for materials

We spent right around $25, though your costs will vary depending on what you already have in the garage.

Time spent

Building our sub box took about an hour and a half. Your project could take more time or less, depending on the complexity of your box's shape, and the tools you have at your disposal. We had a roomy, well-equipped shop.


What you'll need

  • Jigsaw
  • Electric drill with bits for pre-drilling screw holes and driving screws
  • 3/4" MDF (medium density fiberboard)
  • 2" drywall screws
  • Panhead sheet metal screws (1/2" and 3/4")
  • Carpenter's glue
  • Silicon caulk
  • Non-hardening rope caulk
  • Speaker terminal cup — see our full selection of box building supplies
Alpine SWE-1041 10" sub needs a small box

Choosing your subwoofer

When choosing a subwoofer, carefully note the manufacturer's recommended enclosure size, especially if you have limited space in your vehicle. The box volume tells you how big your enclosure needs to be for maximum performance from the sub. The box shown in this article was intended for my Honda CR-V, so I wanted to make sure it wouldn't take up too much space. With that requirement in mind, I chose a 10"  Alpine sub. The manufacturer recommends a box volume of 0.6 to 1.25 cubic feet, so it'll be fine in a small box.

Shop component subwoofers

Planning your subwoofer box design

You can follow these steps to determine the correct dimesnions for your subwoofer box design:

Determine the minimum depth of your box. Measure the depth of your subwoofer and add 2 inches. This measurement is the minimum depth of your box (in this article, the depth refers to the front-to-back dimension of the box, with the woofer being mounted to the front).

Determine the minimum height and width of your box. Measure the frame diameter of your woofer, or check the mounting template that may be included with the owner's manual, to determine the minimum height and width for the front of your box. If you plan to mount a grille, be sure to allow for any additional space that may be needed to accommodate it.

Determine the available space in your vehicle. Measure the height, width, and depth of the vehicle space that you are willing to devote to your subwoofer. If the box must be wedge-shaped to fit, you will need to know the depth at the box's top and bottom.

Sketch out your box. Now's the time to sketch your box on paper using the dimensions you've gathered. The box shown in this article is rectangular, but you may find that a wedge-shaped box fits better in your car or truck. Your sketch may look like one of these:

Subwoofer box design

For our examples, let's use the following external dimensions:

Rectangular box Wedge box
Height: 13" Height: 14"
Width: 14" Width: 18"
Depth: 12" Depth 1: 5"
Depth 2: 8"

Determine the internal dimensions and volume of your box. The above steps identified the external dimensions of the box. To determine the internal volume, just subtract the thickness of the wood to be used for construction. If you're using 3/4" MDF (recommended!), then 2 x 3/4", or 1-1/2", will be subtracted from each dimension.


The internal dimensions for our examples:

Rectangular box Wedge box
Height: 11.5" Height: 12.5"
Width: 12.5" Width: 16.5"
Depth: 10.5" Depth 1: 3.5"
Depth 2: 6.5"

Calculate the internal box volume in cubic inches. Based on the internal dimensions, you can calculate the internal volume of the enclosure using the following formula: Height x Width x Depth = Cubic Volume

Let's plug in some numbers:

Rectangular box:

11.5" x 12.5" x 10.5" = 1,509.375 cubic inches

Wedge box: Since the wedge box has two depth dimensions, we need to find the average depth before we can determine the volume. To find the average depth, add the two depth measurements together, then divide by two. Remember that Depth 1 = 3.5 and Depth 2 = 6.5.

3.5" + 6.5" = 10"
10" / 2 = 5"

So, the average depth of the wedge-shaped box is 5". Plug that dimension into the formula:

12.5" x 16.5" x 5" = 1,031.25 cubic inches

Convert cubic inches to cubic feet. Since most manufacturers will provide the recommended box volume in cubic feet, you'll need to convert the internal volume from cubic inches into cubic feet. This is done by dividing the cubic inches by 1,728.

Rectangular box: 1,509.375 / 1728 = 0.873 cubic feet

Wedge box: 1,031.25 / 1728 = 0.597 cubic feet

Adjust your box's volume to match the sub's specifications. Now, compare the volume of the box you've sketched to the manufacturer's recommendation. If it's too large or too small, you can make small adjustments to one dimension until your box's internal volume matches the manufacturer's recommendation as closely as possible. Often, manufacturers will recommend a range of enclosure volumes. You can get good results with a box that's anywhere inside the recommended range.

Determine the final exterior box dimensions. Once you've identified the correct internal dimensions, it's time to add back that 1-1/2" we subtracted in step 5, to derive the new external dimensions. Double check to make sure that these dimensions will fit properly in your car, and you're ready to move on to construction.

Step-by-step instructions for building the subwoofer box

Step 1

We started by measuring and cutting the main pieces of MDF for the front, sides, back and top of the box, using a table saw with a carbide-tipped blade.

Don't have a table saw? Don't worry. If you purchase your MDF at any large home improvement store, they should be able to cut it for you for a small fee. You could also use a jigsaw, but your cuts may not be quite as smooth (and smooth, flat cuts help to ensure that the box seals well).

We cut seven pieces total — top and bottom, two sides, the back, and two identical pieces for the front (since it was to be a double thickness).

Drawing cutout
Step 2

After the pieces are cut to size, use a compass, or the template that may be included in your subwoofer's packaging, to mark the woofer cutout on one of the identical front pieces.

Fastening the front boards
Step 3

If you choose to use a double-thickness of MDF for the front panel (this method is recommended — it provides an extremely strong, non-resonant mounting surface for the sub), fasten the two identical front pieces together using plenty of carpenter's glue and several sheet metal screws. Also, the double thickness will serve to strengthen the box as a whole.

If you don't use a double thickness of MDF for the mounting surface, you should definitely plan to use bracing elsewhere in the box for added strength. In fact, it's never a bad idea to use bracing no matter what, especially if your box is larger than a cubic foot. The box will be subjected to extreme internal pressure, so the stronger it is, the better.

The easiest way to add bracing is with 2"x2" strips of lumber. Glue and screw these along at least two of your box's internal seams before attaching the top and bottom.

Drill press
Step 4

Using a drillpress, we made a hole near the inside edge of the circle we had traced, large enough for our jigsaw blade to fit in. If you don't have a drillpress, simply use your handheld drill and a large bit.

jig saw

We cut out the circle with a jigsaw, and the woofer opening was complete.

Terminal cup
Step 5

We followed the same drilling/jigsawing procedures to make a rectangular hole in the box's back panel. This would hold the terminal cup, which we installed next.

After running a bead of silicon caulk around the edge of the terminal cup, we screwed it into place using 1/2" sheet metal screws.

Gluing it together
Step 6

Since the back and front pieces were now complete, it was time to fasten everything together. Note: the largest sides of the box should overlap each of the smaller sides to provide the greatest strength. For our box, that meant that the sides were fastened to the front and back first, and the top and bottom were added last.

MDF can be prone to splitting, so we pre-drilled holes for the screws in each of the pieces to be fastened together. After pre-drilling the holes, we squeezed plenty of carpenter's glue between the pieces. The glue, not the screws, is what will ultimately seal the box, so don't be afraid to pour it on.

Screw it together
Step 7

Then, we fastened the pieces together using our cordless drill and 2" drywall screws. Some of the glue will squeeze out during this step — you can wipe it off the outside of the box using a wet rag, but it's OK to leave it on the inside edges (it'll actually help with the seal).

Clamping the box

After you put together the front, back, and sides, you may find that the box is a little out of square — we did. When you screw the top or bottom on, it should pull things back into alignment. Ours gave us just a little bit of trouble, though, so we used a furniture clamp to get things straightened out.

Now it's a box

After you've glued-and-screwed the sides, front, back, top, and bottom, you're just about done.

Shape it up
Step 8

The next step is to drop the subwoofer in and make sure it fits. If the box has gotten a bit out of square, you may find that the sub is now a tight fit — if so, use coarse sandpaper or a rasp to enlarge the opening a little.

Test fit the sub
Step 9

With the subwoofer in place, we used a pencil to mark the screw hole locations, then removed the subwoofer and pre-drilled holes for the mounting screws.

Caulk the inside
Step 10

To make double sure that everything was sealed, we waited for the glue to dry and ran a bead of silicon caulk over all of the box's internal seals. We used a hand-held tube of caulk, since it would be tough to get a caulk gun down inside the box at this point.

Let the caulk cure for 12-24 hours before putting the subwoofer back in. Some silicon caulk releases acetic acid fumes while curing, which have the potential to destroy subwoofer surrounds.

Rope caulk
Step 11

After the caulk had cured, we hooked up speaker wires from the terminal cup to the subwoofer and placed the subwoofer back in the box, using non-hardening rope caulk (found in the weatherstrip section of the hardware store) to seal it down.

Finishing and customizing the subwoofer box

After finishing the box, I couldn't wait to pop it in my CR-V. After the glue and caulk had dried, we hooked it up to the rear channels of my Alpine 4-channel amplifier using 12-gauge speaker cable. It sounded excellent, and the box was definitely sturdy.

However, since naked MDF leaves something to be desired in the looks department, I checked in with one of Crutchfield's installation specialists to get some ideas on customizing a subwoofer box. He offered up plenty of inspiration and installation tips on all kinds of coverings, from vinyl to carpet and beyond!

Thanks to Kelley Blanton, and to Taylor and Boody Organbuilders of Staunton, VA, for the use of their facility and tools.

Now, it's your turn

Following the directions in this article, you should be able to build your own subwoofer box. Be sure to check out our selection of subwoofer installation accessories — we carry a variety of speaker terminals, port tubes, carpet, and other accessories you need to build your box. And if you need help, contact our advisors via phone, chat, or email.

Last updated June 16, 2016
  • jott sajot from philippines

    Posted on 6/8/2015 9:49:43 AM

    nice box for your sub-woofer

  • Brad Counard from Manitowoc,WI.

    Posted on 7/6/2015 1:56:08 AM

    Question, I want to design a ported box for (4) 12" subwoofers. I have to separate the (2) subs from the other (2) subs being that they are different brands and different dimensions (2) Alpine type R,and (2) Pioneer comp. D.V.C subs is there any advice you could give me on constructing this project? Thanks,Brad

  • Alexander Hrabe from Crutchfield

    Posted on 7/7/2015 2:32:10 PM

    Brad, you're thinking in the right direction by separating the subs and keeping things simple. Follow the steps laid out in this article in accordance with the ideal box dimensions for each sub. If you're unsure about the recommended box dimensions, give Pioneer or Alpine tech support (depending on the sub) for advice.

  • baily clifton

    Posted on 7/21/2015 10:48:27 PM

    I wad was wondering on how to make a box for my truck. I have recently bought 4 61/2 inch speakers and a 12 inch sub. I have a 99 f250 pick up

  • Alexander Hrabe from Crutchfield

    Posted on 7/22/2015 9:06:43 AM

    Baily, check the manual for the ideal dimensions for your subwoofer or you may even want to consult the manufacturer's tech support before beginning. Be sure to take accurate measurements of the space you'd like to use in your pick-up, then follow the steps outlined in this article. Good luck!

  • Ted from San Francisco

    Posted on 7/23/2015 11:06:35 AM

    What is the Vcc measurement ? I have an Audison 12 inch sub. thanks .

  • Alexander Hrabe from Crutchfield

    Posted on 7/23/2015 2:06:35 PM

    Ted, contact Audison tech support with the model number. They may be able to help.

  • Alex from san angelo

    Posted on 7/31/2015 12:00:19 AM

    What's the best glue for when it comes to wrap up box w carpet, thanks.

  • Alexander Hrabe from Crutchfield

    Posted on 7/31/2015 7:24:48 AM

    Alex, any wood glue should do the trick. You could also use carpet adhesive. The key is to make sure your application is even. You'll get the best results if you apply the carpet in stages, allowing ample time for one side to dry before applying it to the next.

  • Brad from Aylmer

    Posted on 9/28/2015 12:36:32 PM

    My brother had a sub box made for 2 boxes, I decided to make 2 single boxes for the each of them for him and I. There is a 4 inch hole for the sound in the double box, so do you think a 2 inch hole in the single sub box would be benifitial? To execute the sound better?

  • Alexander Hrabe from Crutchfield

    Posted on 9/29/2015 8:49:41 AM

    Brad, if you're referring to a port size, that will depend on the cubic volume of your box and what frequency you're trying to tune for. You can check the subwoofer owner's manual for suggestions, but searching the internet for "tuning port calculator" should point you to a couple of places that'll help you figure it out.

  • Kenneth Starling from Franklinton

    Posted on 10/5/2015 9:41:12 PM

    I need a 4 ft box tuned at 32 for 2 12s... How do I know where my box is tuned at?

  • Alexander Hrabe from Crutchfield

    Posted on 10/7/2015 11:37:40 AM

    Kenneth, check your subwoofer manual for the ideal dimensions for an enclosure or you may even want to consult the manufacturer's tech support. Once you know those dimensions, give us a call at the number above, and an advisor will help you find the box that's right for you.

  • Chris

    Posted on 10/10/2015 1:41:04 PM

    For dual or triple sub enclosures are they supposed to be completely sealed between the subs? Meaning if I push in on one should the other come out? Several boxes I have purchased do this. The one I built did not. And the sound was lacking.

  • Alexander Hrabe from Crutchfield

    Posted on 10/12/2015 12:14:54 PM

    Chris, it's ideal. An internal wall ensures that each sub gets the right amount of unshared air space for optimum performance, and that structure also makes for a stronger, sturdier box.

  • Shiyam from India

    Posted on 10/22/2015 2:25:08 PM

    What about the power supply?? And how to connect with batteries

  • Alexander Hrabe from Crutchfield

    Posted on 10/25/2015 1:28:36 PM

    Shiyam, for more information about how to install an amplifier, check out this article.

  • Maxx from Virginia beach

    Posted on 11/25/2015 10:29:47 AM

    Trying make a box design for 4 massive summos 8in subs with port trying to come up with best idea

  • Alexander Hrabe from Crutchfield

    Posted on 11/27/2015 10:27:57 AM

    Maxx, check the manual for the ideal dimensions for your subwoofers or you may even want to consult the manufacturer's tech support before beginning. Be sure to take accurate measurements of the space you'd like to use in your vehicle, then follow the steps outlined in this article. Good luck!

  • Oscar from Mexico

    Posted on 12/11/2015 4:36:44 PM

    Is not supposed to have an opening for the air be able to move in and out the box?

  • Alexander Hrabe from Crutchfield

    Posted on 12/14/2015 10:06:50 AM

    Oscar, you're thinking of a ported enclosure, which will give your bass a different sound than a sealed enclosure. Check out this article on the different kinds of sub enclosures for more information.

  • Erick from Oakland

    Posted on 12/22/2015 9:59:04 PM

    Hey I'm a beginner and I have never design or made a sub box. I have a 12 inch Jl audio w7 and I want to how I should build the box. Like mainly the ported design inside the box. Like how long I should make the enclosure or whatever it's called.? Plz help

  • Alexander Hrabe from Crutchfield

    Posted on 12/23/2015 10:19:23 AM

    Erick, check the manual for the ideal dimensions for your subwoofer or you may even want to consult the JL Audio's tech support before beginning. Be sure to take accurate measurements of the space you'd like to use in your vehicle, then follow the steps outlined in this article.

  • Richard Swartz from Rose City

    Posted on 1/4/2016 12:31:51 PM

    My box design to fit in my truck, it will be half round and half square. It's for looks and I've seen one done, it will look well. How do I calculate the volume then?

  • Alexander Hrabe from Crutchfield

    Posted on 1/6/2016 10:48:17 AM

    Richard, it would be worth contacting tech support for your sub manufacturer for recommendations, but searching the internet for "sub box volume calculator" or something similar should point you to a couple of places that'll help you calculate the number you need.

  • Vikas from Jind

    Posted on 1/12/2016 5:43:12 AM

    Sir, i wanted to know the dimension of box for a 8" driver as i wanted to use it at home..... And will it work??

  • Alexander Hrabe from Crutchfield

    Posted on 1/12/2016 9:36:44 AM

    Vikas, check the manual for the ideal dimensions for your subwoofer or you may even want to consult the manufacturer's tech support before beginning. Be sure to take accurate measurements of the space you'd like to use, then follow the steps outlined in this article.

  • Roger from Fort worth TX

    Posted on 5/3/2016 7:36:25 AM

    Why is it that my sub manufacturer calls for a ported box be a certain cubic volume and the port to be a certain diameter and length and tune but every box calculator says something completely different not only different than the manufacturer but than every other box calculator, I also used all the subs t/s parameters why is it none of the means to which I can ascertain what size box and ports I need are so different , how do I figure out which is best to properly fabricate my subwoofer enclosure please help

  • Alexander Hrabe from Crutchfield

    Posted on 5/3/2016 10:48:55 AM

    Roger, you'll get the best results by trusting the manufacturer - they're the ones who designed that sub so they know how to make it perform its best. As far as box calculators go, they are generic tools, so they'll tend to calculate port size and box size a little differently. Hopefully, the dimensions they're calculating are all correct, but the specifics can certainly vary from one calculator to the next.

  • Z28LT1 from Ebro

    Posted on 5/18/2016 7:55:19 PM

    I have a 2001 camaro z28 convertible I want to build a custom box for the trunk I have 2 Sony explode 600 watt amps and 2 Sony explode 12 inch subs that I want to use I've tried contacting Sony but to no avail I seem to have come to a dead end can't find anything online maybe I'm just not looking hard enough any help and advice would be awesome

  • Alexander Hrabe from Crutchfield

    Posted on 5/19/2016 9:25:45 AM

    Ebro, if the Sony subs you have are ones we carry, you'll find ported and sealed volume recommendations (as well as Thiele parameters) under the Details tab of their Crutchfield web page. Keep in mind that if you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.

  • Johnny from Philadelphia

    Posted on 6/5/2016 7:31:06 PM

    What's the difference between an "audiophile " enclosure than ported and sealed . I am having a box built and the shop will use the audiophile specs ,even though on the sheet that came with my IDMAX d2 v4 (it has audiophile specs) the recommended specs are different .

  • Alexander Hrabe from Crutchfield

    Posted on 6/6/2016 10:47:09 AM

    Johnny, if both sets of specs are provided by the manufacturer, your best bet will be to contact their tech team for clarification. Looks like Image Dynamics' number is (866) 933-1414.

  • Dave from Evergreen

    Posted on 6/12/2016 1:31:57 PM

    Is there a reason that MDF is always used? What about solid wood? Or 3/4" plywood? I wanted to make a sealed box out of 3/4" solid Oak to match the interior of my small Motorhome with no carpet on the outside. I plan on using either a single 10" or a 12" higher end JL Audio subwoofer and follow the mfg. specs on sizing the box. I have a SE2300 ARC Audio amp that will be powering the sub in bridged mode. I would like the frequency response to be as flat and true as possible and minimize any resonant frequency. Also should any type of stuffing such as fiberglass insulation added inside the subwoofer? Thanks!

  • Franyi Tineo from Lynn, MA

    Posted on 6/28/2016 9:51:42 PM

    I'm doing research to build my own ported subwoofer box I'm going to need 30cu ft. but to calculate it I'm not sure if the section where the air duct is going to be count as part Of the space I need or I should get 30 cu ft plus the air duct. Please help!

  • Robert Ferency-Viars from Crutchfield

    Posted on 6/29/2016 2:01:50 PM

    Dave, MDF is one of the best forms of plywood. It's heavier, more solid, and more sturdy than lesser grades. It's probably less expensive than solid wood, especially oak. There's no downside to using solid oak, that I know of, so go for it. As for box filler, that's always a personal choice. If you've used it in the past, then go ahead and use it here. A properly sized and tuned box doesn't really need it, but many people like it.

  • Alexander Hrabe from Crutchfield

    Posted on 6/30/2016 9:16:11 AM

    Franyi, I can't imagine that the port would offset the required volume by much, not in a way that would noticeably alter the sound. I wouldn't be too concerned with including the port in that measurement.

  • Gerald Laguerre from Miami

    Posted on 10/3/2016 7:56:11 AM

    What number should the screws be for the 2 in drywall and pan head?

  • Chuck Baldwin from Albuquerque

    Posted on 10/4/2016 1:04:30 AM

    Great article! Has anyone approached you with the idea of using the concrete-pillar forms as tubular sub-woofer enclosures? I created one for one of my JBL 12" bass speakers by cutting the MDH to slip-fit into the inside diameter of the tube glued & screwed from the outside to be flush with the end edge-face of the tube. With the woofer mounted I was able to "tune" the enclosure by sliding the rear wood panel back & forth until I heard the maximum resonant response from the tube itself. Marking that using the rear face of the rear board, I cut the tube then mounted the rear plate with the recessed terminal connector plate mounted much as you describe in your article. My 2nd attempt will be to port the enclosure and "tune" it for maximum port output throughout the 10Hz to 250Hz frequency range. I WAS surprised that no mention was given in the article to the Frequency resonance spec for the speaker, as it can affect the "warmth" versus the "punch" an enclosure can produce. Still, a really good primer for the initiates. Thanks!

  • Robert Ferency-Viars from Crutchfield

    Posted on 10/10/2016 12:31:04 PM

    Gerald, we used eight on each exterior side (left & right) and six on each interior side (top & bottom). So by my math, that's 14 drywall screws. Use however many panhead screws it takes to bolt on your spring terminal cup and another half-dozen or so in the front boards. And when you go to the store to buy screws and a screwdriver, tell the clerk that you absolutely need a right-handed screwdriver. Sometimes they stock the left-handed and right-handed screwdrivers together, and the only way to tell them apart is to scan the barcode to see the stock info on the screen. You're going to be busy and don't have time to go back to the store because you got the wrong screwdriver.

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