How Many Calories Are in Half a Banana? | Size Matters

You probably know a whole banana lands around 110 calories. But half a banana — sliced into oatmeal, blended into a smoothie, or handed to a toddler — is a portion size many people use without thinking twice about the calorie math.

The honest answer isn’t one single number. It shifts with the banana’s size and ripeness. A half banana typically adds between 45 and 67 calories to your day, and the exact count depends on whether you grabbed a small, medium, or large fruit.

Half a Banana Calories by Size

A small banana measuring about 6 to 7 inches provides around 90 calories whole. Half of that is roughly 45 calories. A medium banana (7 to 8 inches) offers about 110 calories, so half clocks in at 53 calories. A large banana (8 to 9 inches) can reach 135 calories, making half about 67 calories.

These figures are based on USDA nutrition data and are consistent across most health sources. The calorie variation comes largely from the fruit’s natural carbohydrate and sugar content, which increases as the banana grows larger.

If you’re tracking calories closely, using a food scale gives the most accurate count. But for everyday estimates, these size-based approximations work well for most people.

Why the Numbers Fluctuate

Bananas don’t come in identical packages. The same variety can vary in calories depending on ripeness, growing conditions, and even the specific bunch. Here’s what makes the biggest difference:

• Ripeness stage: As bananas ripen, starches convert to sugars. Unripe bananas have a higher starch content and slightly fewer available calories per gram than fully ripe ones. The sugar profile shifts too — sucrose drops from about 25% of total sugars in unripe fruit to 11% in overripe fruit.
• Size and weight: A small banana may weigh 80–90 grams, while a large one can top 140 grams. That weight difference alone changes the calorie count by 30 to 40 calories for the whole fruit.
• Growing region: Soil, climate, and farming practices can influence the fruit’s sugar density. Bananas from different countries may have slightly different calorie densities, though the variation is small for most consumers.
• Water content: Bananas are about 75% water. A slightly drier or more hydrated banana will affect both weight and calories per gram, but the effect is minimal in practice.
• Measurement method: “Half a banana” is a visual portion, not a precise weight. Slicing lengthwise vs. crosswise gives different surface areas, and the peel weight (about 30% of total) means half the fruit by volume isn’t necessarily half by weight.

These factors mean the calorie range for half a banana is wider than you might expect — but for most purposes, the 45–67 calorie estimate covers the common sizes people eat.

Nutritional Profile of Half a Banana

Beyond calories, half a medium banana provides a tidy package of carbs, fiber, and potassium. The energy in a banana comes almost entirely from carbohydrates — there’s virtually no fat (about 0.2 grams for half) and very little protein (about 0.65 grams). Harvard’s Nutrition Source puts the banana calorie range between 72 and 135 for a whole fruit, and half a medium banana fits neatly in the middle of that span.

Nutrient	Amount in Half Medium Banana
Calories	53
Carbohydrates	13.5 g
Sugars	7.2 g
Fiber	1.5 g
Protein	0.65 g

The fiber in half a banana is mostly soluble, which can help slow digestion and support stable blood sugar levels. The potassium content is notable too — about 4% of the Daily Value per half, which contributes to electrolyte balance and muscle function.

How to Accurately Portion a Banana

If you’re calorie counting or following a specific macro target, eyeballing “half a banana” can be less reliable than you’d think. Here’s how to get a more accurate portion:

1. Weigh the whole banana with peel. A medium banana typically weighs 130–150 grams with the peel on. Note the total weight, then peel it.
2. Weigh the peeled banana. The edible portion is about 100–120 grams for a medium banana. Split this weight in half for your portion.
3. Use standard lengths. If you don’t have a scale, cut the banana at the midpoint. A 7-inch banana cut in half gives you roughly 3.5 inches — close to the 59-gram half that yields 53 calories.
4. Account for the peel. The peel makes up about 30–35% of the total weight. Don’t include it in your calorie calculation.

Once you’ve done it a few times, you’ll develop a good visual sense. Many people find that half a typical banana from the grocery store is roughly the size of their palm or a cupped handful.

Fitting Half a Banana Into Your Diet

Half a banana is a common portion in smoothies, oatmeal bowls, and snack packs. It’s also a typical serving for people monitoring carbohydrate intake — those 13.5 grams of carbs fit neatly into many low-carb meal plans without going overboard. The USDA defines a medium banana serving as 118 grams, and USDA banana serving guidelines make it easy to scale down to half that size.

Banana Size	Whole Calories	Half Calories
Small (6–7 inches)	90	45
Medium (7–8 inches)	110	53
Large (8–9 inches)	135	68 (approx.)

The table shows how portion size changes the calorie impact. For most people, one to two bananas daily is considered moderate, according to general health guidance. Half a banana offers a convenient way to get the fruit’s potassium and fiber without overdoing the natural sugars.

The Bottom Line

Half a banana provides a small, useful serving of energy — roughly 45 to 67 calories depending on the fruit’s size. The carbs, fiber, and potassium make it a practical addition to breakfast or a pre-workout snack. The exact numbers shift with ripeness and weight, but the estimates here cover the range you’re most likely to encounter.

For precise tracking — whether you’re managing diabetes, counting macros, or following a specific meal plan — a kitchen scale or the serving guidelines from a registered dietitian can give you the certainty eyeballing cannot.