Safe amount of biotin to take for growing your hair?

i'm trying to grow out my hair and i bought biotin pills that are 500mcg each pill and it says to take 1 daily when you eat but i've taken 2 and i was wondering how many i can take to maximize my hair growth but the amount that is safe??? please help thanks! to be more clearer what is the maximum of biotin in mcg can you take safely??