Inside volume of any box from its outside or inside size, in ft³, liters and in³, plus a volume converter.
I measured
Outside
Inside
Outside
Inside
Outside
Inside
Width (in)
Height (in)
Depth (in)
Wall thickness
= 19 mm
Inside volume
2.98 ft³
Liters
84.3 L
Cubic inches
5,146.9 in³
Inside size
30 1/2" × 13 1/2" × 12 1/2"
Convert a volume
1.75 ft3, 50 L or 3024 in3. A bare number is ft³.
Starting points, not guarantees. Your sub’s manual wins: check its recommended box and tuning.
How it works
Enter the width, height and depth, and the wall thickness if you measured the outside. You get the inside volume in cubic feet, liters and cubic inches.
Example: a 30 × 15 × 16 in box in 3/4" MDF is 28.5 × 13.5 × 14.5 in inside: 5,578.9 in³ = 3.23 ft³ = 91.4 L.
To convert, type a volume with its unit: 1.75 ft³ is 49.6 L, and 50 L is 1.77 ft³.
Frequently asked questions
How do I calculate the volume of a sub box?
Take the wall thickness off each inside dimension (twice), multiply width × height × depth in inches, and divide by 1,728 for cubic feet.
How many liters is 1 cubic foot?
28.317 liters. A 2 ft³ box is 56.6 L.
Is this the net volume?
No, it is gross. Subtract the sub’s displacement, the port and any bracing to get net; the box calculator does that.