Tempeh is a fermented soybean product prized for its hearty texture and plant-based protein, but it is also a surprisingly practical source of iron, especially for vegetarians and vegans. This Tempeh Iron Calculator converts a serving size in grams or ounces into an estimated milligrams of iron and shows how that amount fits into your daily iron target. Choose a daily value reference suited to your life stage, and the tool instantly calculates both milligrams and percentage of daily value.
Use it for meal planning, micronutrient logging, or simply to check whether your plant-based proteins are meeting your iron needs. Enter your serving amount, select your unit and daily value reference, then press Calculate. Along with the main result, you will see a small breakdown of the calculation and a practical reminder about pairing tempeh with vitamin C for better non-heme iron absorption.
🍃 Estimate Iron in Tempeh
Enter a serving size to estimate iron content and its percentage of your daily value.
How to Use This Calculator
Start by entering the amount of tempeh you plan to eat. You can type a decimal such as 0.5 for a small snack or 2.5 for a large meal if your unit is ounces, or enter a number in grams. Choose the unit from the dropdown, then select the daily value reference that fits you: the standard adult figure of 18 mg per day, the pregnancy target of 27 mg per day, or the toddler target of 7 mg per day. Press Calculate to see the estimated iron content and the percentage of your chosen daily value.
If a recipe lists tempeh in cups, weigh it on a kitchen scale for the most accurate math. As a rough guide, one cup of chopped tempeh weighs about 166 g, but moisture can vary between brands.
The Math Behind the Iron Estimate
The calculator uses an average iron density of 2.7 mg per 100 g, based on standard nutrient data for cooked tempeh. The core formula is:
Iron (mg) = (Serving weight in grams ÷ 100) × 2.7
If you enter ounces, the weight is first converted to grams using 1 oz = 28.3495 g. The resulting milligrams are divided by the selected daily value and multiplied by 100 to produce a percentage.
Because this is an estimate, actual iron can range from roughly 2.0 to 3.5 mg per 100 g depending on the soybean blend, water content, and fermentation method. Tempeh keeps most of the soybean’s natural iron, and fermentation can reduce some antinutrients that normally interfere with mineral absorption.
Worked Examples
Example 1: A standard 3 oz serving is about 85 g. Iron = (85 ÷ 100) × 2.7 = 2.30 mg. Against the adult 18 mg daily value, that covers about 12.8% of the day’s target.
Example 2: A generous 200 g stir-fry portion contains (200 ÷ 100) × 2.7 = 5.40 mg of iron. On the pregnancy target of 27 mg, that equals exactly 20.0% of the daily requirement.
Example 3: If you enter 4 oz, the tool converts it to 113.4 g and gives (113.4 ÷ 100) × 2.7 = 3.06 mg. For a toddler’s 7 mg target, one serving provides about 43.7% of the day’s iron.
Reference Data: Iron in Common Plant Proteins
| Food | Serving | Iron (mg) |
|---|---|---|
| Tempeh | 100 g | 2.7 |
| Lentils, cooked | 100 g | 3.3 |
| Chickpeas, cooked | 100 g | 2.9 |
| Tofu, firm | 100 g | 5.4 |
| Spinach, cooked | 100 g | 3.6 |
| Quinoa, cooked | 100 g | 1.5 |
Want to compare another plant-based source? The spinach nutrition calculator gives a detailed micronutrient breakdown for leafy greens.
Tips for Better Iron Absorption
- Pair tempeh with vitamin C-rich foods such as bell peppers, broccoli, citrus, or tomatoes. Vitamin C can markedly improve uptake of non-heme iron.
- Avoid coffee or tea within an hour of your main meal when you are trying to maximize iron absorption; tannins can bind to non-heme iron.
- Thoroughly cook tempeh — heat further reduces phytate, a compound in soy that can block iron absorption.
- If you eat a fully plant-based diet, aim for slightly above the standard iron target and consider periodic ferritin testing with your healthcare provider.
Frequently Asked Questions
Is tempeh a good source of iron? Yes for a plant food, although the iron is non-heme and less efficiently absorbed than the heme iron in meat. A 100 g serving of tempeh supplies about 2.7 mg, or roughly 15% of the adult daily value.
Why does my tempeh package show different nutrition numbers? Brands formulate tempeh with different amounts of soybeans, water, and added grains, so iron can range from roughly 2.0 to 3.5 mg per 100 g. The calculator uses a mid-range average and is best treated as an estimate.
Can I eat too much iron from tempeh? Iron overload from food alone is unlikely unless you have a condition such as hemochromatosis. If you have a condition that affects iron storage, discuss your dietary intake with a doctor.
Does cooking change the iron content? Cooking does not destroy iron, though draining away cooking water can remove some water-soluble vitamins. The iron itself stays in the soybean solids, so the main practical effect of cooking is the change in weight from water loss or gain.
Note: Daily value percentages are general reference amounts, not personalized recommendations. For individual nutrition needs, consult a registered dietitian or physician.