By Dr. Michael Torres · Published January 20, 2025 · 6 min read
Banana nutrition facts are worth knowing if you eat them regularly — and most people do. A medium banana contains 105 calories, 27 g of carbohydrates, and 3.1 g of fiber, making it a genuinely nutrient-dense snack that fits almost any dietary pattern. What most nutrition breakdowns miss, however, is how dramatically ripeness changes those numbers. This guide covers everything from calories by size to the glycemic index shift that happens as a banana goes from green to spotted.
Banana Calories by Size
Banana size is the biggest driver of calorie count. The USDA FoodData Central measures raw banana at 89 kcal per 100 g. Here is how that translates by length:
| Size | Length | Weight | Calories |
|---|---|---|---|
| Extra small | < 6 in | ~81 g | 72 kcal |
| Small | 6–7 in | ~101 g | 90 kcal |
| Medium | 7–8 in | ~118 g | 105 kcal |
| Large | 8–9 in | ~136 g | 121 kcal |
| Extra large | > 9 in | ~152 g | 135 kcal |
If you are tracking your intake precisely, weighing your banana on a kitchen scale is more reliable than guessing by length. Alternatively, snap a photo with Caloria and the AI estimates the portion size and calorie count instantly.
Complete Macronutrient Breakdown
Bananas are almost entirely carbohydrate — fat and protein are minimal. Here is the full macro profile per 100 g and per medium banana (118 g), based on USDA data:
| Nutrient | Per 100 g | Per Medium Banana (118 g) |
|---|---|---|
| Calories | 89 kcal | 105 kcal |
| Total Carbohydrates | 22.8 g | 27 g |
| Dietary Fiber | 2.6 g | 3.1 g |
| Total Sugar | 12.2 g | 14.4 g |
| Protein | 1.1 g | 1.3 g |
| Total Fat | 0.3 g | 0.4 g |
The macro split is roughly 93% carbs, 4% protein, and 3% fat. That carbohydrate load sounds high, but the fiber and water content slow digestion considerably — which is why a banana is more filling than a handful of gummy bears with a similar sugar count. For a deeper look at why calorie quality matters alongside quantity, see our article on whether all calories are the same.
Key Vitamins and Minerals
Bananas are best known for potassium, but the micronutrient profile goes further than that.
| Nutrient | Per Medium Banana | % Daily Value |
|---|---|---|
| Potassium | 422 mg | ~9% |
| Vitamin B6 | 0.43 mg | ~25% |
| Vitamin C | 10.3 mg | ~11% |
| Magnesium | 32 mg | ~8% |
| Folate | 24 mcg | ~6% |
Vitamin B6 is the standout. A single medium banana covers a quarter of your daily requirement — more than most common fruits. B6 plays a central role in protein metabolism, neurotransmitter synthesis, and immune function.
ℹ️ Potassium in Context
The 422 mg of potassium in a medium banana is meaningful, but bananas are not the highest potassium food per calorie. Cooked spinach, white beans, and potatoes all deliver more potassium per serving. Bananas earn their reputation partly because they are portable and easy to eat — accessibility matters for consistency.
How Ripeness Changes the Numbers
This is the most overlooked part of banana nutrition. As a banana ripens, its starch converts to free sugars — and this dramatically changes how quickly the carbohydrates enter your bloodstream.
A study published in the European Journal of Clinical Nutrition found that the glycemic index of a banana shifts from 43 (under-ripe) to 74 (over-ripe) — a range that spans from low-GI to high-GI territory.
| Ripeness | Dominant Carb Type | Glycemic Index | Best For |
|---|---|---|---|
| Green (unripe) | Resistant starch | ~43 | Gut health, sustained energy |
| Yellow (ripe) | Mix of starch & sugar | ~51 | General eating, pre-workout |
| Spotted/brown (very ripe) | Free sugars | ~74 | Post-workout glycogen refuel |
Resistant starch in green bananas also acts as a prebiotic, feeding beneficial gut bacteria. If digestive health is a priority, adding an occasional under-ripe banana to your routine is a simple upgrade.
Bananas vs. Other Common Fruits
How does a banana compare nutritionally to other popular fruits? On a per-fruit basis:
| Fruit | Calories | Carbs | Fiber | Sugar | GI |
|---|---|---|---|---|---|
| Medium banana | 105 kcal | 27 g | 3.1 g | 14.4 g | 51 |
| Medium apple | 95 kcal | 25 g | 4.4 g | 19 g | 36 |
| Medium orange | 62 kcal | 15 g | 3.1 g | 12 g | 43 |
| 1 cup mango | 99 kcal | 25 g | 2.6 g | 22.5 g | 51 |
| 1 cup strawberries | 49 kcal | 12 g | 3 g | 7.4 g | 40 |
Bananas are higher in calories than oranges or berries, but they also offer more potassium and vitamin B6 than most other common fruits. The comparison is most useful for understanding trade-offs — not for ranking fruits as "good" or "bad." For a practical look at how different fruits fit into a healthy pattern, see our apple calorie and nutrition breakdown.
Are Bananas Good for Weight Loss?
Yes — the research supports it. Bananas have a reputation for being "too sugary" for weight loss, but the evidence points the other way.
A large cohort study following over 133,000 adults for 24 years found that banana consumption was not associated with excess weight gain. Researchers linked this partly to the fruit's fiber content and water volume, both of which promote satiety.
Three practical reasons bananas work well in a calorie-controlled plan:
- Filling fiber — 3.1 g per banana slows gastric emptying and extends fullness.
- High water content — bananas are about 75% water, adding bulk without significant calories.
- Portable and convenient — easy, peel-and-eat foods are more likely to replace higher-calorie snacks consistently.
For more on building an effective deficit, read our guide on calories and weight loss.
⚠️ Medical Disclaimer
This article provides general nutritional information and is not a substitute for personalized medical or dietetic advice. If you have diabetes or another condition affecting blood sugar, consult a registered dietitian before making dietary changes.
Frequently Asked Questions
How many calories are in a medium banana?
A medium banana (7–8 inches, about 118 g) contains 105 calories, 27 g of carbs, 3.1 g of fiber, and 1.3 g of protein. The exact count varies slightly with ripeness — a very ripe banana has slightly more available sugar and marginally more calories as starch converts.
What is the glycemic index of a banana?
The GI of a banana depends on ripeness. An under-ripe banana has a GI of approximately 43 (low), while an over-ripe banana reaches approximately 74 (high). A typical yellow banana sits around 51, which is moderate — similar to a bowl of oatmeal.
Are bananas good for you?
Yes. Bananas provide a useful combination of fiber, vitamin B6, potassium, and vitamin C. They are easy to digest, widely available, and fit into most dietary patterns. The main consideration is portion size for those closely tracking carbohydrate intake. For context on how to read the numbers on any food label, see our guide to reading nutrition labels.
Do bananas cause weight gain?
Not by themselves. Weight gain is driven by sustained caloric surplus, not by specific foods. A banana's 105 calories are easy to fit within a balanced daily intake. As part of a diet that includes adequate protein and a variety of whole foods, bananas are a weight-neutral or even weight-supportive food. Learn more in our balanced diet guide.
Start Tracking Smarter
Knowing the banana nutrition facts is the first step — understanding how the whole banana fits into your day is where results happen. Caloria makes it effortless: take a photo of your meal or snack and get instant calories, macros, and nutritional context — no manual entry, no guesswork.