A banana's calorie content varies mainly by its size:

• Extra small (under 6 inches, ~81g): about 72–89 calories
• Small (6–7 inches, ~101g): about 90 calories
• Medium (7–8 inches, ~118g): about 100–105 calories
• Large (8–9 inches, ~136g): about 121 calories
• Extra large (over 9 inches, ~152g): about 135 calories

On average, a medium banana contains approximately 105 calories

. Most of these calories come from carbohydrates, with a medium banana having around 27 grams of carbs, 3 grams of fiber, 1 gram of protein, and negligible fat

. The calorie count can slightly vary depending on ripeness, as starch converts to sugar during ripening, affecting digestible carbs and sweetness

. In summary, if you eat a typical medium banana, expect about 100–105 calories.