I've been surprised to see lots of acclaimed people pictures in which the frame cuts off the legs at some point below mid-thigh.
I had (perhaps naively) thought that in people shots, the subject should be head or head+shoulders, or upper body or whole body including feet. Apparently not.
Is there a no-go area cut-off area of the legs? Is it okay to cut off at the ankles, or mid-calf, or at knee level?
Obviously personal taste comes into such questions, but on the other hand there's generally accepted practice and what "looks right".
An odd question - maybe because the 'where to' comes naturally just by looking. If there are any rules, then it's news to me too, but were I to make one, I'd say avoid cutting anywhere below the knees - stumps ain't cool. But cut thighs can generally carry the visual weight of what's on top of the frame.