Well, I thought that at the doctors, you could get a height and weight check, and they'll tell you . But last time i went, currently 14 and 5' 7", and they said I was gonna be 6'2". So just go to the doctors, on a regular check-up and ask them.
I'm 19 and last time I checked I was 6'2" and that was ages ago. I'm still growing too. Everyone always mentions it when I haven't seen them for a while. I need to get checked again really. But my mums like 5'4 or something small like that and my dad is like 5'10. My older brother is taller than me and my younger brother isn't far off me. He's 15.
At age 21 is the maximum that you will actually grow, most people stop at 17-19, but 21 is basically the max. I'm 5' 11 as of now, I'm overweight so there is some pressure on my spine and legs, if I lost the weight I'll almost immediately become 6feet since the pressure is released. I was supposed to be 6' 3" but I became a chubby child.