I want to go back to Lugol's because Iodoral is so expensive. As I was figuring out how much I will need, I realized I got it all wrong to begin with. Prior to switching to Iodoral, I was taking 24 drops Lugol's 2%.
If you are taking 9 tablets of Iodoral, you were getting 45mg of Iodine / 67.5 Iodide per day. Lugol's 2% is usually 2.5mg of Iodine per vertical drop, so you are correct that you would need 18 vertical drops.