If I can find a chart in my million and one bookmarks I'll post. In the meantime, err on the conservative side. YOu only need a few drops (10-15) of e.o. per let's say, 8 oz of carrier oil. I'm pretty heavy-handed, but I'm learning. E.O.s like rosemary, peppermint, eucalyptus are VERY potent. So use your nostrils as a guide. Others like ginger and patchouli are so strong that one single drop can completely change a formulation. Also, I think some e.o.'s can be drying if used in excess. So focus them in on your scalp. I'm thinking of stimulating e.o.s: rosemary, peppermint, etc.
Have fun experimenting and just like any recipe follow the golden rule: You can always add but you can't take away.
hth,
p1