I have an eight month old female GSP. Right now she weighs 45 lbs. How big will she get when mature and when do they stop growing.
Those formulas are going to be close for Ringo. His sire is 65 lbs and right now Ringo is on track to be exactly the same size (height and weight) as Fritz, his sire.
So, for the formulas:
At 4 mos Ringo weighed about 27 lbs.
27 X 2 +10 = 64
At 6 mos Ringo weighed about 51 lbs
51 X .25 + 50 = 62.75