Slot ports -- same calculation as round?

Port Length calculator ; Volume of box in cubic feet, Flare length port required ; Tuning frequency ; Port diameter ; Number of ports

I use to use this website for enclosure calculations, and just wondering if can get something similar but for L slot ports I actually found

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slot machine lucky 7 Port Size Step 6 – Checking Cone Excursion Step 7 – Check Group Delay Step 8