finding the cu. ft

[jrr323 10+ year member]

what would be the cubic feet for my box. the width is 13", its 13" high, and the lenght is 32". its a sealed box with 3/4' mdf. any help is appreciated.

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[mannyb18b]

multiply those numbers than divide by 1728

 

[2loud4u 10+ year member]

or go here

http://www.rockfordfosgate.com/rftech/boxcalculator.asp

 

[Raven 10+ year member]

Take those dimensions, and subtract two times the thickness of your material from each. This will give internal dimensions:

13X13X32 become 11.5X11.5X30.5

Do the math:

11.5^2X30.5 = 4033.625 cubic inches

Divide by 12^3(1728 - the number of cubic inches in a cubic foot) to get the number of cubic feet:

4033.625 / 1728 = 2.334273726851851852 or about 2 1/3 cubic feet.

Subtract displacement of woofer (Between 0.1 and 0.25 cf)

2 1/3 - 1/10 =~ 2 1/5 cube feet

This formula works for all boxes.

My latest one: 16^2x21.5 = 14.5^2X20 = 4,205. 4,205 / 1,728 = 2.43. 2.43 - 0.25(Woofer displacement) - 0.18 (Bracing) = 2.0 cf net.

 

[Wkbdkid 10+ year member]

Take those dimensions, and subtract two times the thickness of your material from each. This will give internal dimensions:13X13X32 become 11.5X11.5X30.5

Do the math:

11.5^2X30.5 = 4033.625 cubic inches

Divide by 12^3(1728 - the number of cubic inches in a cubic foot) to get the number of cubic feet:

4033.625 / 1728 = 2.334273726851851852 or about 2 1/3 cubic feet.

Subtract displacement of woofer (Between 0.1 and 0.25 cf)

2 1/3 - 1/10 =~ 2 1/5 cube feet

This formula works for all boxes.

My latest one: 16^2x21.5 = 14.5^2X20 = 4,205. 4,205 / 1,728 = 2.43. 2.43 - 0.25(Woofer displacement) - 0.18 (Bracing) = 2.0 cf net.

confusing as hell lol but works

wouldnt HxWxD x.75(wood thickness) / 1728 work also