Example Data Table
| Timestamp | Age | Sex | Diet | RDA | Target | Intake | Absorbed | Gap |
|---|---|---|---|---|---|---|---|---|
| 2026-06-10 08:30:00 | 28 | Female | Omnivore | 18 | 19.80 | 14.00 | 2.66 | 5.80 |
| 2026-06-10 08:40:00 | 35 | Male | Vegetarian | 8 | 15.84 | 12.50 | 1.25 | 3.34 |
| 2026-06-10 08:55:00 | 30 | Female | Vegan | 18 | 23.76 | 20.00 | 2.40 | 3.76 |
Formula Used
This tool combines a reference daily iron value (RDA) with two planning multipliers, then compares it to your entered intake.
- Target (mg/day) = RDA × DietMultiplier × TrainingMultiplier
- Total Intake (mg/day) = HemeIron + NonHemeIron
- Absorbed Estimate (mg/day) = (HemeIron × 25%) + (NonHemeIron × NonHemeAbsorption)
- Gap (mg/day) = Target − Total Intake
Vegetarian/Vegan: 1.8× (planning factor)
Vitamin C raises it, inhibitors lower it.
Clamped between 3% and 18%.
How to Use This Calculator
- Enter your age and sex, then select pregnancy/lactation if relevant.
- Choose your diet pattern and training level for an adjusted target.
- Enter estimated daily heme and non-heme iron from foods or labels.
- Select vitamin C and inhibitor levels to estimate non-heme absorption.
- Press Submit to view results above the form.
- Use CSV/PDF buttons to export your recent session history.
Daily iron targets by life stage
This calculator uses age and sex to select a reference target. Children often need 7–10 mg daily. Teens need more during growth. Adult men usually target about 8 mg daily. Many adult women target about 18 mg daily.
Pregnancy and lactation planning data
Pregnancy increases daily needs due to blood expansion. A common reference is 27 mg daily. Lactation often uses about 9 mg daily. Needs vary with diet, labs, and clinical advice. The tool shows these shifts clearly.
Heme and non-heme intake differences
Heme iron comes from meat and seafood. It absorbs more consistently in mixed meals. Non-heme iron comes from plants and fortified foods. Its absorption changes with meal choices. The calculator separates both intakes for clearer tracking.
Absorption factors and meal timing data
Vitamin C can raise non-heme absorption in the same meal. Tea and coffee can lower it near meals. Calcium can also interfere in some cases. The tool estimates absorption between 3% and 18%. This range helps compare meal patterns. Cooking in cast iron can raise meal iron slightly. Pair grains with citrus to improve plant iron uptake.
Diet patterns and adjustment multipliers
Plant-based diets rely more on non-heme sources. Bioavailability can be lower in many mixed diets. A planning multiplier helps compensate for typical absorption limits. This tool uses a conservative 1.8× factor for vegetarian patterns. Use it for planning, not diagnosis.
Tracking, exports, and decision support
After each submit, results appear above the form. The chart compares target, intake, and absorbed estimate. Use mg per day for consistent comparisons. Fortified cereals can add 4–18 mg per serving. Legumes may add 2–6 mg per cooked cup. Session history saves up to 15 entries. Export CSV for spreadsheets and logs. Export PDF for quick sharing with your care team.
FAQs
Is this calculator a medical tool?
No. It gives educational estimates using common reference values. Use lab tests and clinician guidance for diagnosis, supplementation, or treatment decisions.
What should I enter for heme and non-heme iron?
Use food labels, nutrition trackers, or a daily food log. Put meat and seafood iron under heme. Put plant and fortified sources under non-heme. If unsure, enter total as non-heme.
Why does the absorbed estimate seem low?
Only a portion of dietary iron is absorbed. Non-heme absorption varies widely. Vitamin C may raise absorption, while tea, coffee, and calcium may lower it. The estimate is simplified by design.
What does the “gap” value mean?
Gap equals Target minus Intake. A positive gap means intake is below the adjusted target. A negative gap means intake meets or exceeds it. Use gap as a planning signal, not a lab result.
Does training change iron needs?
Training can increase turnover and losses for some people. The calculator applies a small planning multiplier for moderate and high training. If you have fatigue or low ferritin, seek clinical evaluation.
Is there a safe upper limit?
The tool shows a common upper limit guide of 45 mg daily for adults. Some conditions require different limits. Do not supplement high-dose iron without medical supervision, especially with genetic or liver risks.