Bananas are not a low-carb fruit. A medium ripe banana contains about 28 grams of carbohydrates, 15 grams of which come from sugar. That’s more than half the daily carb allowance on a strict ketogenic diet, which typically caps intake at 20 to 50 grams per day. If you’re counting carbs for any reason, bananas land firmly in the higher-carb category among fruits.
How Many Carbs Are in a Banana
A medium ripe banana (about 7 inches long) provides roughly 110 calories, 28 grams of total carbohydrates, and 3 grams of fiber. That puts the net carbs at about 25 grams. There’s virtually no fat and only 1 gram of protein, so nearly all the energy in a banana comes from carbohydrates.
For comparison, half a cup of strawberries has 6.5 grams of carbs. Half a cup of blackberries has 7 grams. Even a medium orange, which most people think of as sugary, comes in at 15.5 grams. A banana nearly doubles that. Among common fruits, bananas sit alongside mangoes and nectarines at the top of the carb scale.
Ripeness Changes the Type of Carbs
The carbohydrate makeup of a banana shifts dramatically as it ripens, even though the total carb count stays roughly the same. A green, unripe banana contains about 21 grams of starch per 100 grams of fruit. By the time it’s fully ripe and spotted, that starch drops to around 1 gram per 100 grams, having converted almost entirely into simple sugars. Ripe bananas average about 17 grams of sugar per 100 grams, a mix of fructose, glucose, and sucrose.
That starch in green bananas is largely resistant starch, a type of fiber that passes through your stomach and small intestine without being digested. It reaches the large intestine intact, where gut bacteria ferment it. This means green bananas produce a smaller blood sugar spike than ripe ones. Research on this type of resistant starch has shown it can reduce both blood sugar and insulin responses in healthy people after a meal. The fiber content also drops significantly as bananas ripen: unripe bananas can have around 14 grams of fiber per 100 grams more than slightly ripe ones.
The glycemic index of a raw banana averages about 51, which falls in the low-to-medium range. That’s moderate compared to white bread (around 75), but the total glycemic load still reflects those 25-plus net carbs.
Bananas on Keto and Low-Carb Diets
A standard ketogenic diet limits carbs to under 50 grams a day, and many people aim for 20 grams. A single medium banana would use up 56 to 100 percent of that daily budget in one snack, leaving almost no room for vegetables, nuts, dairy, or any other food that contains even trace carbs. For keto, bananas are essentially off the table.
On more moderate low-carb plans that allow 50 to 100 grams of carbs daily, a banana is technically possible but still a significant chunk of the day’s allowance. Half a banana is a more practical choice if you want the flavor without the full carb hit.
Lower-Carb Fruits to Consider Instead
If you’re looking for fruit that fits a carb-conscious diet, several options deliver far fewer carbs per serving:
- Watermelon: 5.5 grams per half cup, diced
- Strawberries: 6.5 grams per half cup, sliced
- Avocado: 6.5 grams per half cup
- Blackberries: 7 grams per half cup
- Raspberries: 7.5 grams per half cup
- Plums: 7.5 grams per medium fruit
Berries are the go-to fruit on low-carb and keto diets because they pack more fiber relative to their sugar content. A full cup of sliced strawberries still comes in under half the carbs of one banana.
What Bananas Do Offer
Bananas are high in carbs, but that doesn’t make them unhealthy for people who aren’t restricting carbohydrates. A medium banana delivers 450 mg of potassium, a mineral most people fall short on that plays a key role in blood pressure regulation and muscle function. The 3 grams of fiber supports digestion, and the natural sugars make bananas a quick, portable source of energy before or after exercise.
If you’re choosing between a banana and a candy bar, the banana wins on every nutritional metric. The question is really about context. For someone eating a standard diet of 200 to 300 grams of carbs per day, a banana is a perfectly reasonable snack. For someone targeting ketosis or managing blood sugar tightly, those 25 net carbs per fruit are hard to justify when lower-carb options exist. Choosing a less ripe, slightly green banana can soften the blood sugar impact thanks to the resistant starch, but it won’t meaningfully lower the total carb count on a nutrition label.