If you want to use this calculator, first choose what size driver(s) you are using, then enter how many are in your enclosure. Now, enter your Xmax figure (in millimeters), and the frequency that you need to tune your vent to. And, finally click the "Calculate Minimum" button to get your results. The "Minimum Diameter" box is for round ports, and the "Minimum Area" box is the minimum area required for a square vent. If you need to convert a measurement to/from English/Metric click here, then come back.

 Next, you enter either an inside diameter for the tube you are using if you want a circular port, or the inside dimensions of the square port you are going to build into your box (make sure you click the "Slot Port" button if you are designing a slot port - if you don't understand the difference between a square vent and a slot vent, click here). And finally, press the "Calculate Length" button at the bottom, and your answer will appear in the "Vent Length" box.