Great, inexpensive option for getting your kid's cello off the floor. Included some pics to show a 3/4 size cello sitting pretty -- and no longer on the carpet! I believe it would also work for a 4/4, since the bottom support still has a bit of room for "expansion". Due to the foam pad which resides on the inside of the back support, the cello sits in the stand fairly secure, with no wiggling unless forced. Of course, because of the height involved, it's probably safest to sit it in a corner just in case.
Update Sept. 2019: It does fit a full-size 4/4 cello, see newest pictures. To be on the safe side, it still resides in a corner in case it happens to fall, but it would really have to be knocked into for it to move whilst in the stand. P.S. Having the instruments out and "available" -- instead of sitting in their cases -- is definitely conducive to more practice!