How old is a child ticket for entry? To receive a child rate you must be between the ages of 3 - 17 years old. Related articles Do I have to pay for a under 3 ticket? Can adults visit LEGOLAND Discovery Dallas Fort Worth without children? Do parents have to buy tickets? Can I buy the combo ticket and go to SEA LIFE before we visit LEGOLAND? Can adults visit LEGOLAND Discovery Center without any children?