Iron Intake Calculator
Daily iron needs by age and gender
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Iron Intake Calculator turns the numbers behind daily iron needs by age and gender into a result, step by step. Type Age into Iron Intake; each keystroke re-runs the math. Iron Intake displays each intermediate figure as well. Students and professionals reach for Iron Intake when speed matters. Iron Intake runs in your browser. Health data stays in the tab. Looking for iron intake calculator daily requirement anemia or a quick estimate? Iron Intake covers both. Keep Iron Intake bookmarked for next time. No sign-up or email — Iron Intake answers as you type.
What the defaults give
A 30-year-old man needs about 8 mg of iron a day.
That is the standard adult male requirement. Women of childbearing age need considerably more, because menstrual losses are part of the requirement.
How the requirements divide
The figures follow the widely used dietary reference intakes:
- Adult men, 19 and over: 8 mg a day.
- Women 19–50: 18 mg a day, from menstrual iron loss.
- Women 51 and over: 8 mg a day, matching men after menopause.
- Pregnancy: 27 mg a day, to supply the fetus and the extra blood volume.
- Lactation: 9–10 mg a day, lower than pregnancy because menstruation usually pauses.
Heme versus non-heme
Iron from meat, poultry and fish (heme) is absorbed at roughly 15–35%. Iron from plants and fortified foods (non-heme) is absorbed at about 2–20%, and it is strongly affected by what else is on the plate. That is why the same milligram figure means very different things depending on the source: a vegetarian needs more total iron to reach the same absorbed amount.
What changes absorption
Vitamin C with a meal raises non-heme absorption substantially.
Coffee and tea taken with a meal reduce it — polyphenols bind iron, so leave a gap of an hour or more.
Calcium competes with iron, which is why supplements are usually taken apart from dairy.
Phytates in wholegrains and legumes inhibit absorption, partly offset by soaking and fermenting.
Before you supplement
Iron is one of the few nutrients where more is genuinely risky: excess is not easily excreted and can cause organ damage in people with haemochromatosis or other iron-loading conditions. Symptoms such as persistent fatigue are not a reason to self-supplement — get a blood test and follow the result. This page gives the reference intake, not a diagnosis.
Absorption, not intake, decides whether the requirement is met. Heme iron from meat is taken up at 15–35%, plant iron at 2–20%, so a vegetarian eating 18 mg may absorb less than a meat eater eating 12 mg. Vitamin C with a meal helps, coffee and tea within an hour of eating hinder, and calcium competes directly. Supplementing without a blood test is risky because excess iron is not easily excreted.
Frequently Asked Questions
How much iron does a man need daily?
About 8 mg a day from age 19 onward. Women aged 19–50 need 18 mg because of menstrual losses.
How much iron during pregnancy?
27 mg a day, which is a substantial increase over the non-pregnant requirement and usually needs dietary attention or a supplement.
Why do women need more iron?
Menstrual blood loss removes iron that has to be replaced. After menopause the requirement falls to the same 8 mg as men.
Does coffee block iron absorption?
Yes. Polyphenols in coffee and tea reduce non-heme iron uptake, so leave an hour between the drink and an iron-rich meal.
Is plant iron as good as meat iron?
No. Heme iron is absorbed at 15–35% while non-heme is 2–20%, so vegetarians need more total iron and good vitamin C pairing.
Should I take an iron supplement?
Only on the basis of a blood test. Excess iron is not easily cleared and can be harmful, particularly in iron-loading conditions.
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