If my math is right, one vertical drop is 2.6mg. One horizontal drop would be twice that much, more or less. If you took 10 vertical drops, that would be 26 mg, 20 would be 52, etc.
One vertical drop of Lugol's is 6.5mg. The 2% Lugols is 2/5 of the strength of the 5% Lugols. 2/5 of 6.5 = 2.6.