How will 7 jeans fit me?

i am going into 7th grade and i have always wanted a pair of these. but, i haven't liked the kids style so i had to wait until i could fit in adults. i am a size 12 in kids jeans, and i don't know if theyll fit me yet. could someone find me the measurements or tell me if they will fit me yet? and please don;t tell me i don't need them, because i have already heard that. i just want to know if the will fit me.