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Daily Iron Intake Calculator

Check your daily iron intake against the recommended amount for your age and sex.

Result

Percent of Daily Recommendation
67%
Recommended Daily Amount
18 mg

Based on NIH Office of Dietary Supplements recommended dietary allowances. Menstruating women (roughly ages 19-50) need substantially more iron than men or postmenopausal women to replace iron lost through monthly blood loss.

About the Iron Intake

The Daily Iron Intake Calculator checks how much iron was consumed in a day against the recommended dietary allowance for a given age and sex. It is meant for anyone tracking iron intake from food or supplements, particularly people at higher risk of falling short, such as menstruating women. Enter the milligrams consumed alongside age and sex to see the applicable RDA and the percentage of it reached.

How It Works

The calculator applies a two-tier RDA rule built around a specific risk group: women between ages 19 and 50 are assigned an RDA of 18 milligrams, reflecting additional iron lost through menstruation, while every other combination of age and sex, meaning men of any age and women outside that age range, is assigned a baseline of 8 milligrams. The entered intake is then divided by that RDA and expressed as a percentage.

RDA = 18 mg if sex is female and age is between 19 and 50 inclusive; RDA = 8 mg for all other inputs. Percent of daily recommendation = (iron consumed / RDA) x 100.

Examples

30-year-old woman

Consuming 10 mg of iron places her in the 18 mg RDA tier, so the calculator returns approximately 56% of the daily recommendation.

45-year-old man

Consuming 9 mg of iron falls under the 8 mg RDA baseline that applies to men, so the calculator returns approximately 113% of the daily recommendation.

Advantages

  • Applies the correct RDA automatically based on age and sex instead of requiring a manual lookup of the right reference value.
  • Expresses intake as a percentage, making it easy to see at a glance whether a day's iron consumption fell short of or exceeded the target.
  • Works equally well for food-based or supplement-based iron, since it only needs a total milligram figure.

Common Mistakes

  • Adding up iron from a supplement label and food separately without combining them into one total before entering it, which understates true daily intake.
  • Assuming the 18 mg figure applies to all women, when the calculator only applies it to the 19 to 50 age range.
  • Overlooking that heme iron from meat and non-heme iron from plants are absorbed at very different rates, so two people consuming the same milligram total on paper may absorb noticeably different amounts.

Edge Cases to Watch For

  • The calculator uses only two RDA tiers, so adolescent girls under 19 and women over 50 are both assigned the same 8 mg baseline as men, a simplification rather than a fully age-graded set of brackets.
  • There is no upper limit check, so a very high intake figure, such as from concentrated supplements, simply displays a percentage well above 100% with no separate excess-intake warning.
  • The result is a direct ratio of intake to RDA with no minimum or maximum clamp, so a consumption value of 0 correctly returns 0%.

Common Use Cases

  • A menstruating woman checking whether her typical diet reaches the higher iron RDA that applies to her age group.
  • Someone reviewing a supplement's iron content against a personal daily target before deciding on a dose.
  • A vegetarian or vegan tracking iron intake more closely, since plant-based diets tend to provide iron in the less efficiently absorbed non-heme form.
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

Why is plant-based iron absorbed less efficiently than iron from meat?

Meat, poultry, and fish contain "heme" iron, which the body absorbs relatively efficiently (roughly 15-35%), while plant sources contain "non-heme" iron, which is absorbed less efficiently (roughly 2-20%) and is more affected by other foods eaten at the same time - pairing plant iron sources with vitamin C-rich foods can meaningfully improve absorption.

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Conclusion

This calculator gives a quick percentage-of-RDA check for iron intake using standard age and sex based reference values. Because it only requires a milligram total, age, and sex, it can be rerun daily to track intake against the applicable target over time.

References