Iron Intake Needs Calculator
Estimate your recommended daily iron (RDA) from sex, age and life stage, with the higher target that vegetarian and vegan diets call for.
How it works
target = RDA for sex/age/life stage · × 1.8 if vegetarian or vegan (non-heme iron absorbs less)
Iron RDAs are set by the Institute of Medicine and vary widely by life stage: menstruating women need roughly 18 mg while adult men need only 8 mg, and pregnancy pushes the target to 27 mg. Because iron from plants (non-heme) is absorbed far less efficiently than iron from meat (heme), vegetarians and vegans are advised to target about 1.8 times the standard RDA. Pairing plant iron with vitamin C and avoiding tea or coffee at the meal both improve absorption.
Worked example
A 30-year-old woman eating an omnivore diet has an RDA of 18 mg/day. If she is vegetarian, the guidance rises to 18 × 1.8 = 32.4 mg/day of dietary iron to offset lower non-heme absorption.
Frequently asked questions
Why do women need more iron than men?
Menstruation causes regular iron loss, so women aged 19–50 have an RDA of 18 mg versus 8 mg for men. After menopause the female RDA also drops to 8 mg.
Should I take an iron supplement to reach this?
Not without testing. Excess iron is harmful and the body cannot easily excrete it. Get ferritin and iron levels checked and let a clinician decide whether a supplement is needed.
Does cooking in a cast-iron pan help?
It can add a small amount of absorbable iron to acidic foods like tomato sauce, but it is not a reliable way to correct a deficiency.
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Educational estimate only — not medical or dietary advice. Nutrient reference values are population averages; your individual needs may differ with medical conditions, medications, pregnancy or activity. Talk to a doctor or registered dietitian before making changes.