A medium banana of about 118 grams has roughly 105 calories, according to USDA FoodData Central. Because the count is tied to weight, the honest answer is a range: a small banana is closer to 90 calories, a medium one about 105, and a large banana can reach 120-135. Almost all of those calories come from carbohydrates — a mix of natural sugars, starch, and around 3 grams of fiber.
Calories by banana size
The US Department of Agriculture defines banana sizes by length and weight, which is why the same “one banana” can mean different things. Here is the realistic range:
| Size | Length | Approx. weight | Calories |
|---|---|---|---|
| Extra small | < 6 in | ~81 g | ~72 |
| Small | 6-6.9 in | ~101 g | ~90 |
| Medium | 7-7.9 in | ~118 g | ~105 |
| Large | 8-8.9 in | ~136 g | ~121 |
| Extra large | ≥ 9 in | ~152 g | ~135 |
If you do not have a scale, “medium, about 105 calories” is the safe default most nutrition labels and databases use.
What those calories are made of
A medium banana contains roughly 27 g of carbohydrate, including about 14 g of natural sugar and around 3 g of fiber. It has almost no fat and only about 1.3 g of protein. The fiber matters: it slows digestion, so the sugar in a whole banana is absorbed more gradually than the sugar in, say, a soft drink. That is one reason a banana works as a steady snack before or after activity, giving you accessible energy without the sharp spike of pure sugar.
It is worth putting the “sugar” number in context. The roughly 14 g of sugar in a banana is naturally occurring and comes packaged with fiber, vitamins, and minerals — quite different from 14 g of added sugar in a candy bar, which arrives with none of that. Whole fruit and added sugar are not nutritionally equivalent, even when the sugar figure looks similar on a label.
More than just calories
Bananas are popular partly because they are nutrient-dense for the calories. A medium banana provides roughly 420 mg of potassium (about 9% of the daily value), a good amount of vitamin B6, and some vitamin C and magnesium. Potassium supports normal muscle and nerve function and helps balance sodium in the body, which is why bananas have a reputation as a workout snack — though they are not a guaranteed cure for muscle cramps, which have several possible causes. The vitamin B6 supports metabolism, and the fiber contributes to digestive health and helping you feel full.
Are bananas good for weight management?
No single food makes or breaks a diet, and a banana is a reasonable choice within most eating patterns. At around 100 calories with fiber, it is more filling than many processed snacks of the same calorie count, and its natural sweetness can satisfy a sugar craving. People sometimes worry that bananas are “too high in sugar” to eat while managing weight, but the combination of fiber and nutrients makes a whole banana very different from a sugary drink or dessert. Portion and overall diet matter far more than avoiding a single fruit.
Does ripeness change the number?
Not meaningfully. As a banana ripens and its skin spots, some of its starch converts to sugar, so a very ripe banana tastes sweeter. But the total carbohydrate — and therefore the total calorie count — stays roughly the same. The difference you notice is flavor and texture, not calories.
There is one subtle wrinkle some people care about: greener, less-ripe bananas contain more resistant starch, a type of carbohydrate that acts more like fiber and is digested differently. This does not change the calorie count on a label, but it can affect how the banana feels in terms of fullness and blood sugar for some people. Riper bananas, with more free sugar, tend to taste sweeter and feel like a quicker energy hit. Both are fine choices; it comes down to preference and how you plan to use them — greener for a steadier snack, riper for baking or a sweeter taste.
Fitting bananas into your day
At around 100 calories with fiber and potassium, a banana is a reasonable everyday snack for most people. Pair it with a protein source — a spoon of peanut butter, some yogurt, or a handful of nuts — to make it more filling and to slow the release of its natural sugars even further. Bananas also travel well, need no prep, and are inexpensive, which is a big part of why they are one of the most-eaten fruits worldwide. For another common food number, see how much protein is in an egg, and if you are counting steps to balance intake, our guides to steps in a mile and a healthy daily step count put the activity side in perspective.
This article is for general information and is not medical or dietary advice. Calorie needs vary by person; talk to a doctor or registered dietitian about your own diet.