How to find your port square inches?

[99s10dowork 0]

Maybe this is super simple...but could someone maybe help me with this? how do you calculate square inches of a port? is it just LxW of your port? Ive built my share of boxes and never paid attention to this rule...Thanks guys!

[///M5 2,833]

Square inches is an area, so you measure the area of your port. Not always L*W as it may not be rectangular.