The small intestine in an adult human is typically about 6.5 meters (approximately 21 feet) long. However, its length can vary quite a bit among individuals, ranging from as short as 3 meters (10 feet) to as long as 10.5 meters (about 34.5 feet). The small intestine is called "small" due to its smaller diameter compared to the large intestine, despite being longer in length. It has three parts: the duodenum, jejunum, and ileum, with the ileum being the longest section. The length generally depends on factors like the person's height, and measurements can differ between a living person and postmortem examinations.