Maine coon owners?? how big do they get?

Hi, i'm thinking of adopting a main coon kitten, I have heard they can be big cats, How big can they get? I have a normal domestic cat and i would not like for her to feel intimidated in anyway, the maine coon i'm thinking of adopting is in need of a home and would love to give her one, the only thing holding me back is the size the maine coon may reach in adulthood, I would like to hear from maine coon owners please!