Tips » Weight Training
How low should I go on my squats?
Go as far as your flexibility will allow for a full range squat. Go to 90 degrees for a partial squat, etc. Which is best? Depends on where you are at in your training.
Your full range of motion will be dictated by the length of your leg bones, the tightness of your muscles, flexibility in the hips and ankles, etc. So what one person suggests may not be practical for you.
While 90 degrees has the greatest stress on the knee, there are times when loading a lighter or heavier weight and placing that stress there is desired in order to strengthen and stabilize the joint.
Personally, I think a combination of doing heavy, ass to the grass squats for general bulk and then doing one-legged "King squats" or "pistols" for strength and stability is a solid routine to keep that joint strong and stable.