Iron Intake Calculator
iron intake calculator. Get instant, accurate results. Enter values for instant results with step-by-step formulas.
Reviewed by Rahul Singh, Health & Wellness Specialist
Formula
RDA varies by life stage: Adult male 8 mg, Pre-menopausal female 18 mg, Pregnant 27 mg, Post-menopausal 8 mg | Vegetarians: RDA × 1.8
Iron RDA is based on NIH Dietary Reference Intakes (DRI). The vegetarian multiplier accounts for the lower bioavailability of non-heme iron in plant foods vs heme iron in animal products. The % RDA shows how much of your daily target you're meeting.
Worked Examples
Example 1: 30-year-old vegetarian female
Problem:30F, vegetarian, not pregnant, estimated daily iron intake: 12 mg.
Solution:Base RDA: 18 mg. Vegetarian multiplier: ×1.8 = 32.4 mg. Intake: 12 mg = 37% of RDA. Deficit: 20.4 mg.
Result:32.4 mg RDA, significantly deficient — needs more plant-based iron + vitamin C
Example 2: 25-year-old pregnant woman
Problem:25F, pregnant, omnivore, consuming 20 mg/day.
Solution:RDA during pregnancy: 27 mg. Intake: 20 mg = 74% of RDA. Deficit: 7 mg.
Result:27 mg RDA, slightly low — prenatal supplement likely needed
Frequently Asked Questions
Why do women of childbearing age need more iron than men?
Menstruating women lose iron monthly through blood loss, requiring an RDA of 18 mg/day compared to 8 mg/day for adult men. During pregnancy, iron needs jump to 27 mg/day to support fetal development, expanded blood volume, and placental tissue. After menopause, iron requirements drop to 8 mg/day — the same as adult males.
What are the symptoms of iron deficiency?
Early iron deficiency may be asymptomatic. As stores deplete, symptoms include: fatigue and weakness, pale skin and gums, shortness of breath on exertion, cold hands and feet, headaches, brittle nails, hair loss, restless leg syndrome, and cravings for ice (pagophagia) or non-food items (pica). A complete blood count (CBC) and serum ferritin test are the most reliable diagnostic tools.
What foods are highest in iron?
Heme iron (most bioavailable): beef (2–3 mg/3oz), lamb, liver (up to 10 mg/3oz), oysters, clams (up to 24 mg/3oz). Non-heme iron: lentils (3.3 mg/½ cup cooked), spinach (3.2 mg/½ cup), tofu (3 mg/½ cup), kidney beans (2 mg/½ cup), pumpkin seeds (4.5 mg/oz), fortified cereals (up to 18 mg/serving).
References
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy