How Many Calories Are In A Banana? | Size & Ripeness Guide

You have probably noticed the size of bananas varies wildly depending on the bunch you grab at the store. One skinny banana might look like a snack, while another is thick enough to be a meal on its own. So when someone asks “how many calories are in a banana,” the honest answer is “it depends.”

The USDA FoodData Central database sets a baseline: a medium banana, roughly seven to eight inches long, provides about 105 calories. That number shifts up or down by roughly 30 calories depending on the fruit’s length, weight, and thickness. Here is what you are actually looking at when you reach for the bunch.

How Size Changes The Calorie Count

The easiest way to estimate banana calories is by length, though weight is more precise. A small banana measuring under six inches delivers around 72 to 90 calories. A medium banana (seven to eight inches) bumps up to about 105 calories.

Large bananas, eight to nine inches long, provide roughly 121 calories. Extra-large specimens over nine inches can reach 135 calories. Per the standard USDA guideline, each 100 grams of peeled banana flesh contains 89 calories.

That is roughly the same calorie density as a medium sweet potato or a cup of grapes. The banana’s carbohydrate content shifts accordingly: about 19 grams of carbs for a small banana, 27 grams for a medium, and up to 35 grams for an extra-large one. Fat stays near zero across all sizes, and protein remains a modest 1 gram.

Why The Ripeness Question Matters For Your Goals

Most people assume all bananas are nutritionally identical once peeled. The truth is, the stage of ripeness changes the starch-to-sugar profile noticeably, even though the total calorie count stays roughly the same.

• Green, underripe: High in resistant starch, which functions similarly to fiber. This banana contains more than 3 grams of fiber and has a lower glycemic impact. Some people find greener bananas more filling for this reason.
• Fully yellow, ripe: The standard 105-calorie banana. Starch has mostly converted to sugar, giving it about 15 grams of naturally occurring sugar and 3 grams of fiber. This is the go-to for everyday snacking.
• Overripe with brown spots: Higher in simple sugars and lower in fiber (under 2 grams). The flavor is much sweeter, which makes it ideal for baking but means the energy hits the bloodstream faster.

If you are managing blood sugar concerns, a greener banana may feel more balanced due to the resistant starch. For a quick pre-workout energy boost, a riper banana with visible brown spots might be the better choice because the sugars are more readily available.

Calories Banana Breakdown By Size

The numbers below are based on the USDA FoodData Central database, which sets the standard for nutrition facts in the United States. Keep in mind that these values represent the edible portion without the peel.

Banana Size	Length (inches)	Calories (approx)
Small (under 6 in)	<6	72–90
Medium	7–8	105
Large	8–9	121
Extra Large	>9	135
Cup, sliced	—	134

If you weigh the banana without skin, a 100-gram serving provides roughly 81 calories. A medium peeled banana usually lands close to that mark. For a deeper look at how these numbers shift by exact weight, Healthline breaks down the calorie range by size in detail.

How To Estimate Your Banana’s Calories

You will not always have a food scale or measuring tape handy. Here are a few reliable ways to estimate the calorie count based on visual cues and common kitchen items.

1. Use your phone as a ruler: A banana roughly the length of a standard smartphone (without a case) is a medium banana, around 105 calories. Shorter by an inch or two? That is a small banana, closer to 90 calories.
2. Check the thickness: Length alone doesn’t tell the whole story. A skinny 8-inch banana might be 100 calories, while a plump, thick 8-inch banana of the same length can push 120 calories because the flesh is denser.
3. Weigh once and remember: If you have a food scale, weigh a few bananas over a week. A medium peeled banana is typically about 100 grams (89 calories). An unpeeled medium banana weighs about 120 grams total.
4. Work in cups: If you slice bananas into oatmeal or yogurt, a full cup of sliced banana comes out to about 134 calories. That is helpful for portioning out larger servings.

Most people tend to overestimate banana size when guessing by eye. When in doubt, default to the medium column—it represents the vast majority of store-bought bananas and keeps your counting consistent.

What You Get Besides The Calories

A medium banana delivers more than just energy. It is a solid source of fiber (3 grams), vitamin B6, and potassium, with 1 gram of protein and 0 grams of fat. The health benefits for blood pressure and gut health are broadly supported by research.

Food Item	Calories	Sugar (g)
Medium Banana	105	15
Medium Apple	95	19
Cup of Grapes	104	23
1 oz Almonds	164	1.2

The 15 grams of sugar in a medium banana are naturally occurring and packaged with 3 grams of fiber, which slows digestion compared to processed sweets. For a full breakdown of the vitamin and mineral content, the Harvard banana nutrition facts page provides comprehensive context.

The Bottom Line

Banana calories are straightforward: a medium fruit provides about 105 calories, with a range of 72 to 135 depending on length and thickness. Ripeness shifts the starch-to-sugar ratio but barely changes the total calorie count, so choosing greener or riper is more about immediate energy needs than caloric totals.

For anyone tracking exact macros or managing blood glucose closely, weighing the peeled fruit a few times will train your eye better than any chart can.