Lentils or black beans: which has more protein?
Lentils, mature seeds, cooked, boiled has 1.0× more protein per 100 g, 9.02 g against 8.86 g in Beans, black, mature seeds, cooked. That is 18% of the Daily Value against 18%.
Daily Value 50 g. Per 100 g, so the two are directly comparable.
| Per 100 g | Lentils, mature seeds, cooked, boiled | Beans, black, mature seeds, cooked |
|---|---|---|
| Energy | 116 kcal | 132 kcal |
| Protein | 9.02 g | 8.86 g |
| Total fat | 0.38 g | 0.54 g |
| Carbohydrate | 20.1 g | 23.7 g |
| Dietary fiber | 7.9 g | 8.7 g |
| Protein | 9.02 g | 8.86 g |
What this means for you
They are effectively identical, 9.0 g against 8.9 g per 100 g, and a difference that small is noise rather than a reason to choose. Per cup the lentils come out slightly ahead because a cup of them weighs more, about 18 g of protein against 15 g.
Where they actually differ is elsewhere. Black beans carry a little more fibre. Lentils carry notably more folate, at 181 µg per 100 g, which makes a cup of them most of a day's worth.
The practical answer is to cook whichever you will eat more often. On the numbers that matter, there is nothing to choose between them.
Both are also among the cheapest sources of protein and fibre in any shop, and both improve with soaking, which softens them and reduces some of the phytate that holds on to iron and zinc. Lentils need no soaking and cook in twenty minutes, which is usually the deciding factor on a weeknight.
For scale: the Daily Value for protein is 50 g and for fibre 28 g, so one cup of either covers roughly a third of the protein and half the fibre. Very few foods do both at once, which is the real reason to keep a bag of each in the cupboard.
Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.
The comparison is per 100 g of edible portion, so the two foods sit on the same footing. Real portions differ, and so does how much of the nutrient your body actually absorbs from each food. The guide below has the absorption details.
Lentils, mature seeds, cooked, boiled → · Beans, black, mature seeds, cooked →
Full guide: Protein: who genuinely needs more of it, and what the extra does not do
Data: USDA FoodData Central, FDC IDs 172421 and 173735. Checked 2026-09-15.