Plant-Based Protein Combining Calculator
Combine a legume and a grain to hit a protein target with a complete amino-acid profile — how many grams of each cooked food to eat.
How it works
Legume grams = (target × 0.6 ÷ legume protein per 100 g) × 100 · Grain grams = (target × 0.4 ÷ grain protein per 100 g) × 100
Plant proteins are usually complete but low in one essential amino acid: legumes are short on methionine, while grains are short on lysine. Eating them together — over a day, not necessarily the same plate — yields a complete amino-acid profile, the classic pairing behind rice and beans or hummus on bread. This tool weights about 60% of the protein toward the lysine-rich legume and 40% toward the methionine-rich grain, then converts each share into grams of cooked food.
Worked example
For a 25 g protein target with lentils (9 g/100 g) and brown rice (2.7 g/100 g): 15 g from lentils needs about 167 g cooked lentils, and 10 g from rice needs about 370 g cooked rice — together a complete 25 g of protein.
Frequently asked questions
Do I have to combine proteins at the same meal?
No. Current guidance is that eating a variety of plant proteins across the day gives a complete amino-acid profile; the old rule about combining at every meal has been relaxed. Pairing at a meal is simply convenient.
Which plant foods complement each other?
Legumes (beans, lentils, peas) pair with grains (rice, wheat, oats), and both pair with nuts and seeds. Legumes supply lysine that grains lack, and grains supply methionine that legumes lack.
Are soy foods already complete?
Yes. Soy foods like tofu, tempeh and edamame contain all essential amino acids in good amounts, so they do not strictly need combining — though pairing still adds variety and volume.
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Educational estimate for meal planning, not medical or nutrition advice. Serving thresholds and needs vary by person — check with a dietitian for medical diets.