Subtotal $0.00
Shop Now
Tofu is soy milk that has been curdled with a coagulant and pressed into blocks, a little like making cheese. In USDA data, half a cup of firm tofu made with calcium sulfate has about 181 calories, 22 grams of complete plant protein and about two-thirds of the Daily Value for calcium. Softer styles hold more water, so they carry fewer calories and less protein per bite. Below are the USDA numbers for the main types of tofu, why the coagulant changes the calcium, where soy stands with the FDA, and who should be careful.
Peptide Labs does not sell tofu or soy products. This article is general nutrition information, not medical advice.
Key Takeaways
- Half a cup of firm, calcium-set tofu has about 181 calories and 22 grams of protein in USDA data.
- Calcium depends on the coagulant: tofu set with calcium sulfate is far higher in calcium than magnesium-set tofu.
- Soy protein contains all nine essential amino acids.
- Softer tofu holds more water, so it has fewer calories and less protein per 100 grams.
- Soy is a major food allergen, and NCCIH reports a tyramine interaction between tofu and MAOI antidepressants.
What is tofu and how is it made?
To make tofu, soybeans are soaked, ground with water and strained to give soy milk (see our guide to soy milk). A coagulant is stirred in so the proteins clump into curds, which are then pressed. The two classic coagulants are calcium sulfate and magnesium chloride, traditionally called nigari. A USDA organic program technical review describes magnesium chloride as a coagulant of soy milk for tofu, and FDA lists it as generally recognized as safe. The more water that is pressed out, the firmer the block.
Tofu comes from the same bean as edamame, which are young green soybeans eaten whole, and tempeh, which is made from whole soybeans fermented into a cake. Tofu is not fermented, has a milder flavor and soaks up marinades.
Tofu nutrition: USDA values per serving
The table shows USDA SR Legacy values for firm tofu prepared with calcium sulfate (FDC 172475) per half cup, which USDA weighs at 126 grams. Percent Daily Value uses the FDA reference amounts printed on Nutrition Facts labels.
| Nutrient | Per 1/2 cup (126 g) | % Daily Value |
|---|---|---|
| Calories | 181 | n/a |
| Protein | 21.8 g | 44% |
| Total fat | 11.0 g | 14% |
| Saturated fat | 1.6 g | 8% |
| Carbohydrate | 3.5 g | 1% |
| Fiber | 2.9 g | 10% |
| Calcium | 861 mg | 66% |
| Iron | 3.4 mg | 19% |
| Magnesium | 73 mg | 17% |
| Phosphorus | 239 mg | 19% |
| Zinc | 2.0 mg | 18% |
| Copper | 0.48 mg | 53% |
| Manganese | 1.49 mg | 65% |
| Selenium | 21.9 mcg | 40% |
| Sodium | 18 mg | 1% |
| Cholesterol | 0 mg | 0% |
Plain tofu is naturally very low in sodium and has no cholesterol. Its fat is mostly unsaturated. This USDA entry lists no vitamin B12 or vitamin D, so tofu is not a source of either unless a product label says it has been fortified.
Tofu protein
Tofu protein is complete: Harvard’s Nutrition Source notes that soy protein contains all nine essential amino acids, which is uncommon among plant foods. That makes tofu a practical protein anchor for vegetarian meals. For how it compares with other protein sources, see our guide to high-protein foods.
Types of tofu: calories and calcium compared
Types of tofu are sold by texture: soft or silken, regular, firm, extra firm and fried or baked. The numbers below are per 100 grams so they can be compared directly. Two things stand out. Water content drives calories and protein, and the coagulant drives calcium.
| Tofu type (USDA entry) | Calories | Protein | Fat | Calcium (% DV) | Iron (% DV) |
|---|---|---|---|---|---|
| Firm, calcium sulfate (172475) | 144 | 17.3 g | 8.7 g | 683 mg (53%) | 2.7 mg (15%) |
| Regular, calcium sulfate (172476) | 76 | 8.1 g | 4.8 g | 350 mg (27%) | 5.4 mg (30%) |
| Firm, calcium sulfate and nigari (172448) | 78 | 9.0 g | 4.2 g | 201 mg (15%) | 1.6 mg (9%) |
| Extra firm, nigari (174290) | 83 | 10.0 g | 5.3 g | 282 mg (22%) | 2.0 mg (11%) |
| Soft, calcium sulfate and nigari (172449) | 61 | 7.2 g | 3.7 g | 111 mg (9%) | 1.1 mg (6%) |
| Fried (172451) | 270 | 18.8 g | 20.2 g | 372 mg (29%) | 4.9 mg (27%) |
The two firm entries differ a lot because they describe different products and pressing methods. Store-bought tofu varies just as widely, so the Nutrition Facts label on your package is the number to trust. To find calcium-set tofu, look for calcium sulfate in the ingredient list. For other calcium sources, see our guide to foods high in calcium.
Tofu calories in cooking
Tofu calories rise when it is fried, as the USDA fried entry shows: about 270 calories per 100 grams, mostly from absorbed oil. Baking, steaming, stir-frying with a little oil, or crumbling tofu into a scramble keeps it closer to the raw values. Sauces and marinades can add sodium and sugar, so check the label on seasoned or pre-baked tofu.
Is tofu healthy? What the evidence says
Nutritionally, tofu offers complete protein with little saturated fat, plus meaningful amounts of manganese, copper, selenium and, in calcium-set versions, calcium. The 2020 to 2025 Dietary Guidelines for Americans place tofu in the nuts, seeds and soy products protein subgroup and note that a healthy vegetarian pattern is higher in soy products, particularly tofu. The 2025 to 2030 Dietary Guidelines list tofu among the protein-rich whole foods for vegetarians.
Tofu also provides iron, but it is the plant (nonheme) form. The NIH Office of Dietary Supplements notes that nonheme iron is absorbed less well than iron from meat, and that vitamin C eaten at the same meal improves absorption. Our guide to foods high in iron covers this in more detail.
Soy isoflavones and the FDA soy claim
Soybeans contain isoflavones, mainly genistein and daidzein. NCCIH describes them as compounds similar in structure to the hormone estrogen. Research on whole soy foods differs from research on concentrated isoflavone extracts, so results from supplement studies do not transfer neatly to a block of tofu. If you have a hormone-sensitive condition, ask your clinician how soy fits your diet.
In 1999 FDA authorized a health claim about soy protein and heart disease, found at 21 CFR 101.82. In 2017 FDA proposed revoking it because later studies were inconsistent, saying it would consider a qualified claim instead. As of this review the proposal had not been finalized, so you may still see the claim on some packages. It describes a risk factor, not a promise about any one food.
Who should be careful with tofu
- Soy allergy. FDA lists soybeans among the nine major food allergens, so packaged foods must declare soy on the label.
- MAOI antidepressants. NCCIH reports dangerous rises in blood pressure when high-tyramine soy products, such as tofu and soy sauce, were combined with MAOIs. Fermented and aged soy foods are the usual concern. If you take an MAOI, ask your prescriber or pharmacist which foods to limit.
- Levothyroxine. MedlinePlus notes that foods containing soybeans may affect how levothyroxine works; ask your clinician how to time meals.
- Digestive comfort. NCCIH lists bloating, constipation, diarrhea and nausea among possible soy side effects, mostly from supplements.
Fermented soy foods are covered in our fermented foods guide. If you are unsure whether soy suits a medical diet, a registered dietitian or your clinician can help.
Frequently Asked Questions
Is tofu healthy?
Tofu provides complete plant protein with little saturated fat and no cholesterol. Calcium-set tofu is also rich in calcium. Whether it suits you depends on allergies, medicines and your overall diet.
How much protein is in tofu?
In USDA data, half a cup of firm calcium-set tofu has about 22 grams of protein. Softer types have less because they contain more water.
How many calories are in tofu?
Per 100 grams, USDA lists about 61 calories for soft tofu, 76 to 83 for regular to extra firm entries, 144 for one firm entry and about 270 for fried tofu.
Why does tofu calcium vary so much?
Calcium comes mostly from the coagulant. Tofu set with calcium sulfate is much higher in calcium than tofu set with magnesium chloride alone. Check the ingredient list.
Is tofu a good source of iron?
It provides plant (nonheme) iron, about 19% of the Daily Value per half cup of firm calcium-set tofu in USDA data. Eating a vitamin C food at the same meal improves nonheme iron absorption, according to NIH.
Does tofu contain estrogen?
No. It contains isoflavones, plant compounds similar in structure to estrogen. Ask a clinician if you have a hormone-sensitive condition.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Soy Milk: Nutrition, Fortification and Soy Milk vs Milk, Tempeh: What It Is, USDA Nutrition, Protein and Tempeh vs Tofu, Edamame: USDA Nutrition per Cup, Protein, Calories and Benefits.