Sorry, at about 20Kg the Baby Throne starts to get tight so it would be better to move on to the standard toilet trainers available that simply make the toilet hole smaller. 20Kg is the weight of an average 4 year old but if you have a special needs child and they still fit go ahead. We have had great feedback on this. Always be in attendance and do not leave them alone! It is always possible to fall off the Baby Throne even if unlikely.