How Much Fiber in a Banana? - New Health Advisor You get about 3.1g of fiber from a medium banana - it also includes 1g of soluble fiber. It implies that your aim should be to eat at least 8g of bananas a day to enjoy its cholesterol-lowering benefits. Here is more about how much fiber you get from different-sized bananas. 1 extra small (less than 6" long) (81 g): 2.1 g.