The small intestine in adults typically measures between about 3 to 7.6 meters (10 to 25 feet) in length, with variations depending on the individual and measurement methods. Common estimates place it around 5.5 to 7 meters (18 to 22 feet) long

. More detailed breakdowns include:

• Duodenum: approximately 25 to 30 cm (about 10 to 12 inches) long, the shortest section

• Jejunum: about 2 to 2.5 meters (roughly 8 feet) long

• Ileum: about 3 to 3.5 meters (around 9 to 11.5 feet), the longest section

Overall, the small intestine is a long, highly folded tube that fits coiled within the abdominal cavity, with length varying by person height and measurement conditions (longer in taller individuals and when measured postmortem)

. Its diameter is about 2.5 to 3 cm (1 inch), which is why it is called "small" despite its length

. In summary, the small intestine length ranges roughly from 10 to 25 feet (3 to 7.6 meters), commonly around 18 to 22 feet (5.5 to 7 meters) in adults.