Iron Requirement Calculator

Work out iron requirement instantly with clear inputs, formula shown and shareable results.

About Iron Requirement Calculator

Applies the group-specific iron reference intake and raises it by 80 percent for plant-based diets, as guidelines advise for lower non-haem absorption.

Formula

Iron requirement

Reference intakes: 8 mg men, 18 mg premenopausal women, 27 mg in pregnancy; vegetarian requirements are about 1.8 times higher

Worked example

With the default values below, Iron Requirement Calculator returns Adjusted iron requirement of 18.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Groupone of Adult man, Premenopausal woman, Postmenopausal woman, Pregnancy, Child 4 to 8 years: Premenopausal woman
Dietone of Mixed diet with meat, Vegetarian or vegan: Mixed diet with meat
Current iron intakeaccepts 0–100 mg: 12 mg

Results

Adjusted iron requirement: 18.00 mg/day
Reference intake for the group: 18.0 mg/day
Shortfall: 6.00 mg/day
Share of the requirement met: 66.7%

Step by step

1Values used
2Iron requirement
3Adjusted iron requirement= 18.00 mg/day
4Reference intake for the group= 18.0 mg/day
5Shortfall= 6.00 mg/day
6Share of the requirement met= 66.7

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why is non-haem iron absorbed poorly?

It must be reduced before uptake and is inhibited by phytate, calcium and polyphenols; vitamin C counteracts this.

Can too much iron be harmful?

Yes. The upper limit is 45 mg a day, and unnecessary supplementation is harmful in haemochromatosis.