A medium banana (about 118 grams) has roughly 105 calories, 27 grams of carbohydrates, 1 gram of protein, and 0 grams of fat. It’s almost entirely a carb source, which makes it one of the simplest whole foods to log if you’re tracking macros.
Full Macro Breakdown
Here’s what a single medium banana gives you:
- Calories: 105
- Carbohydrates: 27–28 g
- Sugars: 14–15 g (naturally occurring)
- Dietary fiber: 3 g
- Protein: 1 g
- Fat: 0 g
If you track net carbs (total carbs minus fiber), a medium banana comes in around 24 grams. The sugar is a mix of glucose, fructose, and sucrose, all naturally present in the fruit rather than added. Potassium is the standout micronutrient at about 450 mg per banana, roughly 10% of what most adults need daily.
How Ripeness Changes the Macros
The total carbs in a banana stay roughly the same whether it’s green or spotted brown, but the type of carbohydrate shifts dramatically. A green, unripe banana is 70–80% starch by dry weight, and much of that is resistant starch, a type of fiber your small intestine can’t break down. By the time a banana is fully ripe and yellow, it contains only about 1% starch. Nearly all of that original starch has converted into simple sugars.
This matters for blood sugar. Bananas score between 31 and 62 on the glycemic index depending on ripeness. A green banana sits at the low end, causing a slower, more gradual rise in blood sugar. A fully ripe banana with brown spots lands closer to 62, a medium GI rating. For a ripe banana, the glycemic load ranges from about 11 for a very small one to 22 for a very large one. If you’re managing blood sugar, choosing less-ripe bananas gives you a meaningfully different response from the same fruit.
How Banana Size Affects the Numbers
Bananas vary quite a bit in size, and a large banana from the grocery store can easily weigh 30–40% more than a small one. A medium banana is defined as roughly 118 grams (just over 4 ounces of edible fruit), but if you regularly grab the biggest ones in the bunch, you could be eating closer to 130–135 calories and 33–35 grams of carbs. Weighing one or two on a kitchen scale gives you a quick sense of where your usual pick falls. For tracking purposes, you can scale the macros proportionally: every extra 10 grams of banana adds roughly 9 more calories and 2.3 more grams of carbs.
Bananas Compared to Other Fruit
Bananas have a reputation as a high-sugar fruit, but the comparison with other popular options is closer than most people expect. A medium apple has about 95 calories, 25 grams of carbs, and 19 grams of sugar. A medium banana has 105 calories, 27 grams of carbs, but only 14 grams of sugar. The apple actually contains more sugar per serving, though it edges ahead on fiber with 4 grams versus the banana’s 3.
Where bananas do stand out is in how calorie-dense they feel. Because they’re lower in water content than most fruits, they pack their carbs into a smaller, more portable package. That density is what makes them a favorite pre-workout snack: easy to eat, fast to digest, and almost pure carbohydrate energy.
Where Bananas Fit in a Macro Plan
With virtually no fat and only a trace of protein, bananas are a pure carb food. That makes them easy to slot into most eating plans. If you’re running a higher-carb diet for endurance training or muscle recovery, a banana before or after a workout is one of the fastest whole-food options for restocking glycogen. Pairing one with a protein source like Greek yogurt or a handful of nuts balances out the macro profile and slows digestion, which keeps blood sugar more stable.
For lower-carb or keto diets, a full banana uses a significant chunk of a daily carb budget. Half a banana blended into a smoothie with a fat and protein source can be a workable compromise if you want the flavor and potassium without the full 27-gram carb hit. Choosing a smaller, greener banana also gives you more resistant starch and fewer net digestible carbs, though the difference is modest in absolute terms.