How many carbs are in kidney beans?
Kidney beans has 19.1 g of total carbs per 1/2 cup (89 g) — about 14.2 g net carbs after 4.9 g of fiber. That's 21.5 g of carbs per 100 g, roughly 7% of the 275 g Daily Value.
USDA FoodData Central · red, canned, drained · FDC 174285
Carbs by portion
| Portion | Total carbs | Net carbs | Fiber | Sugar | Calories |
|---|---|---|---|---|---|
| 1/2 cup (89 g) | 19.1 g | 14.2 g | 4.9 g | 3.4 g | 110 |
| 100 g | 21.5 g | 16 g | 5.5 g | 3.8 g | 124 |
| 1 oz (28 g) | 6.1 g | 4.5 g | 1.6 g | 1.1 g | 35 |
Net carbs = total carbs − fiber (the carbs that raise blood sugar, used in keto/low-carb tracking). Values computed from USDA per-100 g data (FDC 174285, SR Legacy). red, canned, drained.
A 1/2 cup of canned kidney beans (89 g) carries about 19.1 g of total carbohydrate — but the number that counts for keto, low-carb and blood-sugar tracking is net carbs, and that lands much lower at roughly 14.2 g. The gap is fiber: kidney beans bring about 4.9 g of fiber in that same half-cup, and fiber is carbohydrate your body never turns into glucose. Per 100 g the total is 21.5 g of carbs, of which 5.5 g is fiber, so net works out to 16.0 g per 100 g. When people picture rice-and-beans as a heavy carb plate, the beans are doing less of the carb damage than the total implies.
Why net carbs come in so much lower
With a refined starch like white rice or white bread, there’s almost no fiber, so net carbs ≈ total carbs and nearly every gram hits your bloodstream. Kidney beans are the opposite story: nearly a quarter of their carbohydrate is fiber, the part that gets subtracted to reach net and that doesn’t raise blood sugar. That’s why a 19.1 g total becomes a 14.2 g net per half-cup. The same fiber that lowers the net number also slows digestion, so the remaining carbs release gradually rather than spiking — kidney beans are a genuinely low-glycemic food, which is the whole reason they anchor so many diabetic-friendly and Mediterranean-style meals.
How kidney beans fit a low-carb plan
For strict keto (20–50 g net carbs a day), kidney beans are usable but not free: a half-cup at 14.2 g net is a meaningful share of the budget, and a full cup roughly doubles it to near 28 g. On a flexible low-carb or diabetic-friendly plan they fit more comfortably, because the fiber means you’re getting a filling, protein-bearing food for fewer net carbs than the total would suggest — a much better deal per gram than the rice they’re usually served with. Treat them as a slow carb: portion-controlled, paired with protein and vegetables, they behave very differently than a refined-starch side of the same carb count.
If you want the other side of the macro picture, see protein in kidney beans — and for any canned version you’re tracking, read the label’s own total carb and fiber lines to do the net-carb math yourself.
Frequently Asked Questions
How many carbs are in a 1/2 cup of kidney beans?
About 19.1 g of total carbohydrate in a 1/2 cup serving of canned, drained red kidney beans (89 g), which is 21.5 g per 100 g (USDA FDC 174285). But that total includes 4.9 g of fiber, so the figure that matters for low-carb tracking — net carbs — is lower, around 14.2 g per 1/2 cup.
What are the net carbs in kidney beans?
Roughly 14.2 g net carbs per 1/2 cup — total carbs (19.1 g) minus fiber (4.9 g). Unlike rice or bread, kidney beans carry a lot of fiber relative to their carbs, so net comes in well below total. That fiber is also why beans digest slowly instead of spiking blood sugar the way a refined starch does.
Are kidney beans keto or low-carb?
Strict keto, usually no — even 14.2 g net carbs in a 1/2 cup is a big chunk of a 20–50 g daily budget, and a full cup roughly doubles it. On a more flexible low-carb plan they fit better, especially in small portions, because the fiber means you get a filling, nutrient-dense food for fewer net carbs than the total suggests. They're a slow carb, not a no-carb.
Do kidney beans spike blood sugar?
Much less than refined starches. Kidney beans are a low-glycemic food: the ~4.9 g of fiber per 1/2 cup, plus their protein, slows digestion so the carbohydrate releases gradually rather than all at once. That steadier curve is exactly why beans show up on diabetic-friendly and Mediterranean eating patterns — though portion size and what you eat alongside them still matter.
Why does the fiber in kidney beans matter for carbs?
Fiber is carbohydrate your body doesn't digest into glucose, so it's subtracted out to get net carbs and it doesn't raise blood sugar. Kidney beans pack about 5.5 g of fiber per 100 g, so nearly a quarter of their total carbohydrate is fiber. That's what turns a ~19 g total into a ~14 g net figure and keeps the glycemic impact gentle.
When was this data last verified?
2026-06-04, against USDA FoodData Central FDC 174285 (Beans, kidney, red, canned, drained solids; SR Legacy). We re-verify reference pages periodically and update when the underlying USDA entry changes.
Whole-food values are USDA reference data, not a Labelgrade (that score is for branded packaged products). See our methodology and the macro calculator to turn this into a daily target.