How Much Calories Is a Banana? | A Simple Breakdown

A medium banana (118g) contains about 105 calories, according to the USDA.

You grab one on your way out the door—no wrapper, no plate, no cleanup. That banana seems like a simple, no-thought snack. But later, when you’re logging your meals or just wondering, the question pops up: how many calories was that?

The honest answer depends mainly on size and ripeness, but a medium banana lands at roughly 105 calories. This article breaks down the numbers by size, ripeness, and what else you’re getting with each bite.

Calories in a Banana by Size

Size is the biggest factor. The USDA uses a medium banana (7 to 8 inches long, about 118 grams) as its standard. That banana delivers 105 calories, 27 grams of carbs, and 3 grams of fiber.

A small banana (6 to 7 inches) runs closer to 90 calories. A large banana (8 to 9 inches) bumps up to around 121 calories. An extra-large banana (9 inches or more) can reach 135 calories. If you slice a cup (about 150 grams), you’re looking at 134 calories.

So if you’re grabbing whatever’s in the bowl, the calorie range is roughly 90 to 135. The difference of 45 calories isn’t huge, but it can add up if you eat several a day.

Why Banana Size Is Easy to Misjudge

Most people don’t measure bananas before eating them. They grab one, peel it, and it’s gone. That’s why it helps to have a mental picture of what a “medium” banana actually looks like.

• Visual cues at the store: Bananas sold in bunches are often medium-sized. Look for a banana that spans about the length of your hand from wrist to fingertips.
• Weight vs. length: Weight is more reliable than length. A medium banana weighs around 118 grams. If you have a kitchen scale, a 120-gram banana is right on target.
• How calories scale: For every 10 grams of extra banana, you add roughly 9 calories. So a 130-gram banana is about 115 calories.
• Bagged vs. loose: Loose bananas at the checkout are often larger because they look more impressive. If you want consistent calories, pick from the bunch.
• The “two-portion” banana: A very large banana (over 9 inches) counts as two fruit servings in some dietary guidelines. The USDA considers one medium banana a single serving.

Knowing these cues helps you estimate more accurately without needing to measure every time. A small mental calibration goes a long way.

What Else Is in That Banana?

Calories are just part of the story. A medium banana also provides 27 grams of carbohydrates (including 14 grams of sugar and 3 grams of fiber), 1.3 grams of protein, and almost no fat. It’s also a top source of potassium—about 422 mg, or 9% of the Daily Value.

The carb content climbs with size, but the fiber stays fairly steady around 3 grams for a medium banana. For a precise breakdown by weight, the USDA banana calories page lists full nutrition data per 100 grams and per medium fruit.

How Ripeness Affects Calories and Nutrition

The calorie count stays nearly the same as a banana ripens—the fruit doesn’t lose or gain energy. But the type of carbs and fiber change noticeably. Here’s what shifts as your banana goes from green to spotty.

1. Starch converts to sugar. Green bananas are mostly resistant starch. As they ripen, that starch turns into simple sugars (glucose, fructose, sucrose). The total carb mass stays the same, so calories don’t budge.
2. Fiber decreases. A peer-reviewed study in PMC found that unripe bananas contain roughly 18 grams of fiber per 100 grams. That drops to 4–5 grams in ripe fruit and about 2 grams in overripe fruit. So a spotty banana has less fiber than a green one.
3. Glycemic index shifts. Bananas have a low glycemic index of 48 on average. But the GI rises slightly as the banana ripens because sugars are more quickly absorbed. Still, it remains low to moderate.
4. Micronutrients remain stable. Potassium, vitamin B6, and other vitamins don’t change significantly with ripeness. So you get the same mineral benefits regardless of how spotty the peel is.

If you’re after maximum fiber, choose greener bananas. For a sweeter, easier-to-digest snack, go with ripe or even overripe fruit. Either way, the calorie count is virtually identical.

Banana Calories in Context

How does a banana compare to other common fruits and snacks? A medium banana (105 calories) sits in a similar range to other portable fruit options. The table below shows a few comparisons.

Bananas come in slightly higher than apples and oranges, but they also deliver more fiber and potassium than most fruit. For a more detailed look at how size affects the numbers, the Banana Calorie Range article breaks down every variation from tiny to jumbo.

Compared to a granola bar (often 150–200 calories) or a handful of nuts (160–200 calories), a banana is a relatively low-calorie, whole-food option that satisfies hunger without much added processing. It’s a convenient choice for a quick energy boost before a workout or as part of a balanced snack.

The Bottom Line

A banana’s calorie count depends mostly on its size—small ones run about 90 calories, medium ones 105, and large ones up to 135. Ripeness doesn’t change the total calories but does affect fiber content and sugar composition. Pairing a banana with a protein source (like yogurt or nut butter) can make it a more satisfying snack.

If you’re tracking calories for weight management or blood sugar control, a registered dietitian can help you adjust banana portions to fit your specific daily target and health goals without guesswork.