Subwoofer Box
Volume Calculator

Interactive tool Sealed & ported All brands

What this calculator is for

You've sketched out a box on paper and you want to know if the inside will actually be the right size for your subwoofer. Enter your planned external dimensions and the calculator works out the net internal volume after accounting for the wood thickness and anything else taking up space inside — driver, port, and bracing. It then tells you whether that volume is in the right range for your sub.

Choose your box type

Sealed and ported boxes have different recommended volume ranges, so pick your type first.

Sealed

Tight, accurate bass. More forgiving of volume variations. Best for most music types.

Ported (Vented)

More output at a tuned frequency. Louder but less flexible. Great for hip-hop and EDM.

Your subwoofer size

Select your driver size so the calculator knows what volume to aim for. If your sub's spec sheet lists a specific recommended volume, enter that too — it will override the general range for a more accurate verdict.

Driver size inches

Spec sheet volume cu ft optional

Driver size	Sealed (cu ft)	Ported (cu ft)
8"	0.3 – 0.5	0.5 – 0.75
10"	0.5 – 0.75	0.75 – 1.25
12"	0.75 – 1.25	1.25 – 2.0
15"	1.5 – 2.5	2.5 – 4.0
18"	3.0 – 5.0	4.0 – 6.0

Your planned box dimensions

Enter the outside dimensions of the box you plan to build, and the thickness of the material you're using. 3/4" MDF is the most common choice for subwoofer enclosures.

W Width — left to right H Height — top to bottom D Depth — front to back All external measurements

Width inches

Height inches

Depth inches

Material thickness

Internal displacements

All optional — enter 0 if unsure

Anything inside the box takes up space and reduces the net volume. If you're not sure about a value, leave it at 0 — the calculator will still give you a useful result, just slightly optimistic.

Driver displacement optional

The sub's basket and motor extend into the box. Typical values: 8" ≈ 0.04 ft³ · 10" ≈ 0.07 ft³ · 12" ≈ 0.10 ft³ · 15" ≈ 0.16 ft³. Check your sub's spec sheet for an exact figure — or leave at 0 if you don't have it.

Displacement per driver cu ft

Number of drivers

Port displacement ported boxes only

The port tube takes up space inside the box. Round port: π × r² × length ÷ 1728. Slot port: width × height × length ÷ 1728. Most single-port builds use 0.02–0.05 ft³.

Total port displacement cu ft

Bracing displacement optional

Internal braces stiffen the panels but reduce volume. Leave at 0 if you have no internal bracing planned.

Total bracing displacement cu ft

Net internal volume

—

cubic feet

—

cubic inches

—

liters

Calculation breakdown