How do you figure out Native American ancestry?

My Great Grandma on my mothers side was %100 cherokee. My father was exactly half (blackfoot and chippewa). Is there any way to figure out percentile for me? I know it's not like with dogs or whatever lol But Ive been trying to figure it out in my head but i don't know the guidelines. I do know i have alot (maby just under half if not exacly half). and no it's not for the American Indian benefits, like most Indians I am just proud lol