Seitan, tofu and tempeh are often grouped together as plant proteins, but they are made very differently. Seitan is mostly cooked wheat gluten, tofu is coagulated soy milk, and tempeh ferments whole soybeans.
Side by side per 100 g
| Per 100 g | Seitan | Firm tofu | Tempeh |
|---|---|---|---|
| Calories | ~158 | 144 | 192 |
| Protein | ~31.6 g | 17.3 g | 20.3 g |
| Fat | ~0.9 g | 8.7 g | 10.8 g |
| Carbohydrate | ~8.8 g | 2.8 g | 7.6 g |
Seitan is the most protein-concentrated in this comparison, but the other foods bring different nutrients and textures.
Tofu calcium depends on the coagulant
The USDA firm tofu reference is made with calcium sulfate and contains about 683 mg calcium per 100 g. Tofu made mainly with magnesium salts can be much lower.
Tempeh is a denser whole-soy food
Tempeh keeps the soybean structure and provides about 20 g protein/100 g along with about 11 g fat. It is also more calorie-dense than many tofu products.
Seitan can be surprisingly high in sodium
The product used here lists 440 mg sodium per 57 g, roughly 770 mg/100 g. Other brands can differ substantially because sodium comes largely from the recipe.
Seitan, tofu and tempeh can all fill the ‘protein food’ role, but they are made from different raw materials and should not be treated as interchangeable nutritionally. Seitan is concentrated wheat gluten, so it is usually high in protein for its weight but unsuitable for anyone with celiac disease or a wheat allergy. Tofu is coagulated soy milk and varies widely with firmness and the coagulant used. Tempeh is made from whole fermented soybeans, which gives it a denser texture and generally preserves more of the bean’s fiber. The package label is the best place to confirm exact numbers.
Protein quality is also different from simply counting grams. Soy provides all essential amino acids in useful proportions and is widely used as a complete plant protein. Wheat gluten is relatively low in lysine, so seitan benefits from being eaten as part of a varied diet that includes legumes, soy foods or other lysine-rich ingredients. That does not make seitan ‘bad protein’; it means a single food does not need to provide every amino acid perfectly at every meal. Over the day, variety solves most practical amino-acid concerns for people eating enough total protein.
Minerals depend heavily on processing. Calcium-set tofu can be an excellent calcium source, while tofu made with other coagulants may contain much less. Tempeh often contributes iron, magnesium and fiber because the whole soybean remains in the product. Seitan can be low in some micronutrients unless the recipe includes enriched flour, legumes or seasonings, and prepared versions may be high in sodium. Comparing only protein per 100 grams can therefore hide meaningful differences in fiber, calcium, sodium and overall ingredient quality.
In the kitchen, the best choice often depends on texture and dish. Tofu absorbs sauces and ranges from silky to extra-firm; tempeh has a nutty flavor and firm bite; seitan is chewy and works well where a meat-like texture is useful. Rotating among them is often more practical than declaring one the universal winner. Choose plain or lightly seasoned products when you want control over sodium, and build the rest of the meal with vegetables, whole grains and varied fats. Nutrition comes from the whole plate, not only the protein number on the front.
Which one makes the most sense?
Seitan is efficient when protein is the priority and gluten is not a problem. Tofu offers protein plus unsaturated fat and potentially meaningful calcium. Tempeh combines concentrated soy protein with a chewy fermented-bean matrix.
Serving size can change how the comparison feels at the table. A typical tofu or tempeh portion may be larger than a compact serving of seitan, so protein per 100 g is useful for comparing concentration but does not automatically predict what you will eat in one meal. Prepared products also vary: flavored tofu, marinated tempeh and seasoned seitan can add sodium, sugar or oil. If you are choosing among them for everyday meals, compare the nutrition label at the portion you actually use and consider protein alongside fiber, calcium, sodium, total calories and dietary restrictions such as soy or gluten avoidance.
Sources
- USDA FoodData Central — firm tofu with calcium sulfate — Calories, protein, fat and calcium.
- USDA FoodData Central — tempeh — Calories and macronutrients.
- Upton's Naturals — Traditional Seitan — Current label normalized to 100 g.