Human intestines are only twenty to thirty feet long; most commonly they are between twenty five and twenty eight feet for an adult when inside the body. The small intestine is the longest of the two intestines at twenty to twenty three feet long. The large intestine is only five feet long. Children's intestines are shorter than adult's intestines because both the child and the intestine are still growing. There is a myth that if you stretch out human intestines from only one person, they would stretch around the world but this is just a myth with no truth to it.