A medium banana (about 118 grams of edible fruit) contains 105 calories. That makes it one of the most convenient, portion-controlled snacks you can grab, with nearly all of those calories coming from carbohydrates.
Calories by Banana Size
Not all bananas are the same size, and the calorie count scales proportionally with weight. The 105-calorie figure is based on USDA data for a medium banana weighing 118 grams. A small banana closer to 100 grams will run about 90 calories, while a large one around 135 grams lands near 120. The extra-large bananas you sometimes see at the store can reach 135 calories or more.
Keep in mind that roughly 37% of a banana’s total weight is the peel. A whole banana that weighs 180 grams on a kitchen scale only gives you about 115 grams of actual fruit. If you’re tracking calories by weighing your food, weigh just the peeled portion for an accurate count.
What’s Inside Those Calories
Almost all of a banana’s energy comes from carbohydrates. A medium banana has about 27 grams of total carbs, broken down into 15 grams of sugar, 3 grams of fiber, and the rest as starch. Protein is minimal at 1 gram, and fat is essentially zero.
The 15 grams of sugar is a mix of glucose, fructose, and sucrose. That sounds like a lot, but the 3 grams of fiber slows absorption enough that a banana doesn’t spike your blood sugar the way candy or juice would. The fiber also contributes to the feeling of fullness that makes bananas surprisingly satisfying for their calorie count.
How Ripeness Changes the Nutrition
A green banana and a brown-spotted banana taste completely different, and their internal chemistry reflects that. As a banana ripens, its starch gradually converts into sugar. A green banana is starch-heavy, while a very ripe banana with brown spots is almost entirely sugar. This is why ripe bananas taste so much sweeter.
Here’s the part that surprises most people: the total calorie count barely changes. Research published in PLOS ONE found that the energy content of bananas at different ripeness stages differed by only about 13 calories per banana. What changes is how your body processes those calories. Green bananas contain more resistant starch, a type of starch that passes through your small intestine without being fully digested. Your body actually extracts fewer usable calories from a green banana than the label would suggest.
Ripeness also affects your blood sugar response. The glycemic index of an unripe banana is around 42, which is considered low. A ripe yellow banana scores about 51 (medium), and an overripe banana with lots of brown spots climbs to around 62. If you’re managing blood sugar, choosing slightly less ripe bananas gives you a slower, more gradual energy release.
Bananas Compared to Other Fruit
At 105 calories, a banana is on the higher end for a single piece of fruit. A medium apple has about 95 calories, a medium orange around 65, and a cup of strawberries just 50. But bananas are also denser in carbohydrates, which makes them a better option when you need quick energy before or after exercise. The tradeoff is straightforward: more calories, but also more fuel.
Banana Chips Are a Different Story
Fresh bananas and banana chips are not nutritionally comparable. One cup of banana chips (72 grams) packs 374 calories, more than three times what you’d get from a fresh medium banana. Most commercial banana chips are fried in oil, which dramatically increases the fat and calorie content. If you’re snacking on banana chips thinking they’re a lighter choice, the numbers don’t support that. Even a small handful can easily match or exceed the calories in a whole fresh banana.
Potassium and Other Nutrients
Bananas are best known for their potassium content, delivering about 422 milligrams per medium fruit, which covers roughly 9% of the daily recommended intake. Potassium helps regulate fluid balance, muscle contractions, and nerve signals. It’s one reason bananas are a go-to for athletes dealing with cramps, though the evidence for that specific use is more tradition than science.
You also get a solid dose of vitamin B6, which supports brain function and helps your body convert food into energy. A single banana provides about 25% of your daily B6 needs. There’s a modest amount of magnesium and vitamin C as well, though not enough to make a banana a standout source of either.