What is the actual length of the large intestine? of sm intestine? time it takes for a meal to completely go thru system, mouth to exit?

Variable, but...: Roughly large intestine (colon) is 5 feet long & small intestine is 20 feet long. Figure 4-6 hours to empty stomach completely, 17 hours to digest food thru small bowel, & 1-3 days to absorb thru colon. This calculates to a bell-curve distribution of GI transit such that normal american stool frequency varies from 3x/day to once every 3-4 days. Calculate yours by examining stool for "marker" food.