- The different % are just they way some manufactors made it, watered out, maybe; but that is the option for many of us. I have tried all of them, all worked. The 12% sold in Europe is slightly weaker than the standard 5%.
(Because they count in the iodide, standard lugols would then be a 15% according these measures.)
Back to the easy way. On the bottle it says how much in each drop. Now.. count how many drops in the very dropper from the bottle. Then take one or two droppers full or a half full, depending how much you want to take. Very approx, but easy.