Subwoofer Vent Equations Calculator

Home Theater Systems Car Audio Formulas

Subwoofer Box Comparison Calculator:
Compare bandpass, sealed and vented frequency output graphs for a subwoofer in one program.
Solving for minimum port or vent diameter for a vented box or enclosure.
minimum port vent diameter


driver effective diameter (D)
linear displacement maximum (Xmax)
box ore enclosure frequency(fb)
number of ports (Np)


driver effective diameter (D)
= 0
= 0
linear displacement maximum (Xmax)
= 0
= 0
box ore enclosure frequency(fb)
= 0
= 0
number of ports (Np)
= 0
= 0


minimum port or vent diamter (Dmin)

Other Units:

Change Equation
Select to solve for a different unknown
Subwoofer Box and Speaker Enclosure
vent or port length vent or port length
minimum vent or port diameter minimum vent or port diameter
k values:
vent has one free end and one flanged=0.732
vent has two free ends=0.614
vent has two flanged ends=0.850
Lv=length of port or vent
Dv=diameter of port or vent
Dmin=minimum diameter of port or vent
Np=number of ports or vents
Vb=volume of box
fb or Fb=tuning frequency
k=end correction factor
Sd=surface area of subwoofer
Vd=driver displacement volume
Xmax=maximum linear displacement of driver

References - Books:
See 6 on reference page

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