A one-cup serving of cooked beans typically contains 35 to 45 grams of total carbohydrates, but 10 to 17 of those grams come from fiber your body doesn’t digest. That puts most beans in the range of 20 to 30 grams of net (digestible) carbs per cup. The exact number depends on the variety, how you prepare them, and whether you count fiber separately.
Carbs by Bean Variety
Not all beans are created equal when it comes to carbohydrates. Here’s what you’ll find in a one-cup cooked serving of the most popular varieties:
- Black beans: about 41 g total carbs, 15 g fiber, roughly 26 g net carbs
- Pinto beans: about 45 g total carbs, 15 g fiber, roughly 30 g net carbs
- Kidney beans: about 40 g total carbs, 13 g fiber, roughly 27 g net carbs
- Navy beans: about 47 g total carbs, 19 g fiber, roughly 28 g net carbs
- Chickpeas (garbanzo beans): about 45 g total carbs, 12 g fiber, roughly 33 g net carbs
- Lentils: about 40 g total carbs, 16 g fiber, roughly 24 g net carbs
Canned beans have similar carb counts to home-cooked, though some brands add sugar in the sauce. Check the label if you’re buying baked beans or beans in tomato sauce, which can bump the total carbs significantly.
Green Beans Are a Different Story
If you’re watching carbs closely, green beans (and their cousin, wax beans) are in a completely different category. A one-cup serving of green beans has only about 7 grams of total carbs with roughly 3 grams of fiber, leaving just 4 grams of net carbs. That’s because green beans are picked young and eaten pod and all, before the starchy seeds inside have a chance to develop. They behave more like a vegetable than a legume on your plate.
The Lowest-Carb Legumes
Edamame (young soybeans) and black soybeans sit at the bottom of the carb scale among legumes. A half-cup of shelled edamame has 9 grams of total carbs and 4 grams of fiber, yielding just 5 grams of net carbs. That’s less than a quarter of what you’d get from the same amount of kidney beans. Black soybeans are even lower. If you’re on a keto or very low-carb diet and miss eating beans, soybeans are the closest substitute that still feels like a legume.
Why Bean Carbs Hit Your Blood Sugar Slowly
The carbohydrates in beans don’t behave like the carbs in bread or pasta. Beans have some of the lowest glycemic index values of any starchy food. Chickpeas score as low as 10 on the glycemic index, black beans around 30, and kidney beans around 34. For comparison, white bread scores about 75 and white rice around 73. This means the sugar from beans enters your bloodstream gradually rather than in a spike.
Two things explain this slow release. First, beans are packed with fiber, and almost all of it is the insoluble type. USDA data shows that in most beans, insoluble fiber outweighs soluble fiber by a ratio of roughly 4 to 1 or higher. Red kidney beans, for example, contain about 1.4 grams of soluble fiber and 5.8 grams of insoluble fiber per 100-gram serving. That insoluble fiber creates a physical barrier that slows digestion of the starches packed alongside it.
Second, beans contain resistant starch, a type of carbohydrate that passes through your small intestine undigested, similar to fiber. Cooked beans contain roughly 3 to 5 grams of resistant starch per 100 grams of dry weight. Here’s where preparation gets interesting: if you cook beans and then let them cool to room temperature before eating (or refrigerate them), the resistant starch content increases to around 5 grams per 100 grams. Pinto beans form the most resistant starch during cooling, while chickpeas form the least. So a cold bean salad is, in a measurable way, lower in digestible carbs than a freshly cooked pot of beans.
Counting Bean Carbs for Blood Sugar Management
The CDC defines one “carb serving” as roughly 15 grams of carbohydrates. By that standard, a full cup of most cooked beans counts as about 2.5 to 3 carb servings. A half-cup serving, which is what most meal plans recommend, lands closer to 1.5 carb servings. That half-cup portion is a practical starting point if you’re trying to keep your carb intake steady across meals.
Despite the moderate carb count, beans bring enough protein and fiber to offset the impact on blood sugar in a way that most starchy foods can’t. Chickpeas are roughly 20% protein by weight, and lentils hit about 21%. That combination of protein, fiber, and slow-digesting starch is why beans are recommended rather than restricted for most people managing their blood sugar. The key is portion awareness: measure your serving rather than eating straight from the pot, and you can fit beans comfortably into most eating plans.
How Preparation Changes the Carb Count
Dried beans that you soak and cook at home give you the most control. The soaking water absorbs some of the simple sugars (the ones responsible for gas, incidentally), and draining it removes a small fraction of the total carbs. Cooking time also matters: resistant starch drops sharply in the first 15 to 30 minutes of cooking, then stabilizes. Overcooking beans into a very soft mush breaks down more of that resistant starch, making the remaining carbs easier to digest and faster to absorb.
Canned beans are pre-cooked and ready to eat, so their resistant starch levels are already at the lower, stabilized range. Rinsing canned beans washes away the starchy liquid and any added sodium or sugar, which can trim a gram or two of carbs from the label’s number. For the lowest effective carb count, rinse canned beans, chill them, and use them in a cold dish like a salad or dip. You’ll get the benefit of both reduced simple sugars and increased resistant starch from the cooling process.