Bananas are one of the most common fruits people ask about after a diabetes diagnosis. They are cheap, easy to carry, and sweet, which is exactly why people worry about them. This guide gives you the numbers for a banana by size and ripeness, compares it with other fruit, and shows how to test what a banana does to your own glucose.
Quick answer: A banana is a carbohydrate food, and a medium one has roughly 27 grams of carbohydrate, about 3 grams of fiber, and about 14 grams of sugar. Many people with diabetes include bananas in their eating plan, and no fruit is automatically off limits. What matters is the portion, how ripe it is, what you eat with it, and your own glucose response. This is general education, not medical advice. Your care team can tell you how many carbohydrate grams fit a meal or snack for you.
What is in a banana
The USDA has more than one entry for raw banana, and the numbers differ a little because they describe different samples. The table shows two of them, per 100 grams of edible banana, so you can see the range. Both come from USDA FoodData Central, and we read them through the GetFoodFacts mirror of the April 30, 2026 release.
| USDA entry | Carbs (g) | Fiber (g) | Sugars (g) | Starch (g) |
|---|---|---|---|---|
| Bananas, raw (SR Legacy, FDC 173944) | 22.8 | 2.6 | 12.2 | not shown on page |
| Bananas, ripe and slightly ripe, raw (Foundation Foods, FDC 1105314) | 23.0 | 1.7 | about 15.8 (sum of listed sugars) | 3.66 |
Both entries land near 23 grams of carbohydrate per 100 grams. The second entry lists glucose, fructose, and sucrose separately, so we added them to get about 15.8 grams of sugars. The first entry shows less sugar and more fiber, which could reflect samples at different stages of ripeness, though the pages do not say. For a rough rule, think of the edible part of a banana as a little under one quarter carbohydrate by weight.
How size changes the carbs
A banana is not one standard portion. A small one and an extra large one can differ by 12 to 16 grams of carbohydrate. The table uses a published size guide that says its carbohydrate figures are based on USDA data. We could not confirm the exact USDA weights behind each row, so treat these as approximate.
| Size | Length | Carbs (approx., g) |
|---|---|---|
| Extra small | under 6 in | 19 |
| Small | 6 to 7 in | 23 |
| Medium | 7 to 8 in (about 118 to 126 g edible) | 27 |
| Large | 8 to 9 in | 31 |
| Extra large | 9 in or longer | 35 |
For a medium banana, the same guide gives about 3 grams of fiber and 14 grams of sugar. That matches what you get by scaling the USDA per-100-gram values to about 118 grams: 26.9 grams of carbohydrate, 3.1 grams of fiber, and 14.4 grams of sugars. The practical point is simple. If you are counting carbohydrates, a large banana is not the same as a small one, and the sticker on a bunch will not tell you which you have.
Does ripeness matter?
It can. As a banana ripens, starch turns into sugar. One reference describes a green banana as about 25 percent starch by weight, falling below 1 percent within days of ripening, while sucrose rises from about 0.3 percent to roughly 11 percent. That reference does not name its source, so we treat the exact percentages as approximate. The direction, though, matches the USDA entries above: the ripe entry lists clear amounts of glucose, fructose, and sucrose.
Glycemic index (GI) estimates for bananas vary by study and by ripeness. The same reference gives about 30 to 41 for green or unripe bananas and about 51 to 60 for fully ripe ones, without naming the studies. We did not find a separate figure for overripe bananas. GI measures how fast a food raises glucose compared with a reference food in a test group, so it is a guide, not a prediction for you. Green banana flour is also reported to contain a lot of resistant starch, but that is a processed product, not a banana you peel.
| Stage | What changes | Published GI estimate |
|---|---|---|
| Green or unripe | More starch, firmer, less sweet | about 30 to 41 (source not named) |
| Yellow, fully ripe | Starch largely converted to sugars | about 51 to 60 (source not named) |
| Spotted or overripe | Even sweeter and softer | no separate figure found |
If your numbers rise a lot after a ripe banana, trying a less ripe one is a reasonable experiment. It is not a guaranteed fix, and you should still count the carbohydrate in it.
How a banana compares with other fruit
The table scales USDA per-100-gram values to common portions, so the carbohydrate, fiber, and sugar columns are our arithmetic from USDA data. Per typical portion, a medium banana comes out highest of the seven fruits shown, with mango, grapes, apple, and blueberries in a similar but slightly lower band, and oranges and strawberries lower.
| Fruit | Portion | Carbs (g) | Fiber (g) | Sugars (g) |
|---|---|---|---|---|
| Banana, medium | about 118 g edible | 26.9 | 3.1 | 14.4 |
| Blueberries, 1 cup | 148 g | 21.5 | 3.6 | 14.7 |
| Strawberries, 1 serving | 147 g (about 1 cup) | 11.3 | 2.9 | 7.2 |
| Apple (Red Delicious), small | 158 g | 22.3 | 3.6 | 16.6 |
| Orange (navel), 1 serving | 154 g (about 1 cup of sections) | 19.2 | 3.4 | 13.1 |
| Grapes, 1 cup | 126 g | 22.8 | 1.1 | 19.5 |
| Mango, 1 cup pieces | 165 g | 24.8 | 2.6 | 22.6 |
The USDA entries behind these rows are SR Legacy records: banana 173944, blueberries 171711, strawberries 167762, Red Delicious apple 168201, navel orange 169917, red or green grapes 174683, and mango 169910. The apple and orange portions use the NLEA serving or small-apple weights on the source pages. A larger apple will carry more.
Worked example: how much fruit is 30 grams of carbohydrate?
Suppose a snack plan allows about 30 grams of carbohydrate. That number is only an illustration, not a recommendation, because your own target depends on your medicines, goals, and care team. Using the USDA carbohydrate per 100 grams, here is the amount of each fruit that supplies 30 grams. The arithmetic is carbohydrate target divided by carbohydrate per 100 grams, times 100.
| Fruit | Edible amount for 30 g carbs | Portions from the table above |
|---|---|---|
| Banana | 132 g | 1.1 |
| Blueberries | 207 g | 1.4 |
| Strawberries | 391 g | 2.7 |
| Apple | 213 g | 1.3 |
| Orange | 240 g | 1.6 |
| Grapes | 166 g | 1.3 |
| Mango | 200 g | 1.2 |
The pattern is easy to see. You get about 130 grams of banana for the same carbohydrate that comes with roughly 390 grams of strawberries. That does not make strawberries better or bananas bad. It means the portion you can fit depends on the fruit, and a banana is a more concentrated source.
Pairing a banana with protein or fat
A common tip is to eat fruit with a protein or fat food, such as nuts, nut butter, yogurt, or cheese, instead of on its own. The idea is that a mixed snack digests more slowly. We did not find a source that quantifies this for bananas in people with diabetes, so we will not promise a number. The honest version is that some people see a smaller rise with a paired snack and some do not. Counting the carbohydrate in everything you eat still applies, because nut butter and yogurt can add their own.
How to test your own response
- Check glucose right before you eat the banana.
- Eat the banana by itself or as part of a planned meal, and write down the size and ripeness.
- Check again at one hour and two hours, or look at your CGM trace for that window.
- Repeat with a smaller or less ripe banana, or with a pairing, and compare.
Our post-meal glucose tracker is built for this kind of comparison, and how to read your CGM data explains what the curve means. For context on targets, see the normal blood sugar chart and ask your care team which range applies to you.
Common mistakes
- Treating all bananas as one serving. A large banana can have about 31 grams of carbohydrate, a small one about 23 grams.
- Cutting out fruit completely. Fruit also supplies fiber and potassium. The goal is a portion you can account for.
- Forgetting the extras. Banana bread, banana chips, and smoothies change the math, and their labels matter. See how to read nutrition label carbs.
- Judging from one reading. One banana and one glucose reading is a single data point. Repeat it a few times.
- Assuming green is always safe. A less ripe banana may raise glucose less, but it still has carbohydrate.
Questions to bring to your appointment
- How many grams of carbohydrate should a snack or meal have for me?
- Does my medicine change how I should handle fruit?
- Would a CGM or a few planned meter checks help me see how fruit affects me?
- Can a dietitian help me build a fruit plan around my numbers?
Frequently asked questions
Can people with diabetes eat bananas?
Many people with diabetes eat bananas. A banana is a carbohydrate food, so it counts toward your carbohydrate for the meal or snack. A medium one has about 27 grams of carbohydrate, and the best portion for you depends on your plan and your care team.
How many carbs are in a banana?
About 27 grams in a medium banana, based on USDA data of roughly 23 grams of carbohydrate per 100 grams of edible banana. A small banana is closer to 23 grams and a large one about 31 grams. The values are approximate because bananas vary.
Is a green banana better for blood sugar than a ripe one?
Published glycemic index estimates are lower for green bananas, roughly 30 to 41, than for ripe ones, roughly 51 to 60, but the reference we found did not name its studies. A less ripe banana may raise glucose less for some people, and it still contains carbohydrate. Test it with your own meter or CGM.
Is a banana worse than an apple or an orange?
Per typical portion, a medium banana has more carbohydrate, about 27 grams, than a small apple at about 22 grams or a navel orange serving at about 19 grams. Fiber and portion size differ too. None of these fruits is off limits, and the right choice depends on your numbers.
Should I eat a banana with peanut butter or yogurt?
Pairing fruit with protein or fat is a common suggestion, but we did not find a source that measures the effect for bananas in diabetes, so we do not promise a result. The pairing also adds its own carbohydrate and calories. Try it and compare your readings.
Do bananas raise blood sugar fast?
Any carbohydrate food raises glucose, and how much and how fast varies by person, portion, and ripeness. A banana has fiber, which slows things somewhat, but ripe bananas have more sugar than green ones. Check glucose before and one to two hours after.
How many bananas can I eat a day with diabetes?
There is no single number. Count the carbohydrate in the banana toward your day, and ask your care team or a dietitian for a daily carbohydrate range. Some people plan around one banana, or half of one, and some prefer other fruit.
About the author: Charles Kirkland is the founder of Metabolic Clarity Labs and author of The Journey Back. He is not a physician. This is general education, not a medically reviewed treatment plan.
Sources checked October 31, 2026. Discuss personal decisions with a qualified clinician. Do not start, stop, or change prescribed treatment based on this article.
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