How many carbs are in a banana?
A medium banana has about 29g of carbohydrate and 25g of net carbs. Size and ripeness move that number, so here it is by portion.
Carbs by portion
| Portion | Total carbs | Fiber | Net carbs |
|---|---|---|---|
| 1 medium banana (126g) | 28.8g | 3.3g | 25.5g |
| 1 small (101g) | 23.1g | 2.6g | 20.4g |
| 1 large (136g) | 31.1g | 3.5g | 27.5g |
| 1 cup, mashed (225g) | 51.4g | 5.8g | 45.5g |
| 100 grams | 22.8g | 2.6g | 20.2g |
Net carbs
A medium banana has about 25g of net carbs, which is total carbs (29g) minus fiber (3g). Net carbs are the part that raises blood glucose. See the net carbs guide for when to use net instead of total.
Glycemic index of a banana
The glycemic index of a banana is about 51. A green, less ripe banana sits lower, in the 40s, because more of its starch is still resistant starch. A spotty, very ripe banana climbs into the high 50s as that starch turns to sugar.
For diabetes
A medium banana is about 29g of carbs, which is a real single-food load. The fiber slows the rise a little compared with juice, but it still counts toward your meal total. A smaller or greener banana carries fewer fast carbs. Match it to your insulin ratio and pair it with protein or fat to soften the spike. Most U.S. care teams dose on total carbs, not net. See the diabetes carb-counting guide.
Keto and low carb
One medium banana has about 25g of net carbs, which is at or above a typical day's keto budget of 20 to 30g. Bananas do not fit most keto plans. A few slices folded into a larger meal can work if you count them.
Good to know
Ripeness changes how a banana behaves more than how many carbs it holds. A greener banana keeps more resistant starch and digests slower. A very ripe, spotty one has more free sugar and a higher glycemic index. Dried banana chips are a different food entirely, often 35g of carbs or more in a small handful.
Full nutrition (per 100g)
- Calories: 89.0 kcal
- Carbohydrate: 22.84g
- Fiber: 2.6g
- Sugars: 12.23g
- Protein: 1.09g
- Fat: 0.33g
Stop looking up carbs one food at a time
CarbZen reads the carbs off a photo of your whole plate in about 3 seconds, checked against USDA data. 7 days unlimited, then 30 scans a month, free.
Get the appFrequently asked questions
How many carbs are in a banana?
A medium banana (126g) has about 29g of carbohydrate. A small banana has about 23g and a large one about 31g.
How many net carbs are in a banana?
A medium banana has about 25g of net carbs, which is total carbs (29g) minus about 3g of fiber.
Are bananas OK for diabetics?
Yes, in a portion that fits your plan. A medium banana is about 29g of carbs, so count it, lean toward a smaller or greener one, and pair it with protein or fat to slow the rise.
Is a banana keto?
Not usually. One medium banana has about 25g of net carbs, close to a full day's keto budget.
Does ripeness change a banana's carbs?
The total carbs stay about the same, but a riper banana has more sugar and a higher glycemic index, so it raises blood sugar faster than a greener one.