For personal informaion?

I am going to crochet a doily and have been out of school for a while so can't remember how to figure this out. I even looked it up on weights and measurements and still at a loss. I have to buy 6 of thread 20 grams/3/4 ounces each. Can you help by figuring out conveting the grams to ounces and then the total amount of ounces I would have to buy. This all the information I have regarding the amount of thread I would need to complete the project. Thank you.