Iron Intake Calculator Formula

Understand the math behind the iron intake calculator. Each variable explained with a worked example.

Formulas Used

Recommended Iron

daily_iron = base_iron * is_vegetarian

Upper Limit

upper_limit = age <= 13 ? 40 : 45

Variables

VariableDescriptionDefault
ageAge(years)30
is_vegetarianDietary Pattern1
base_ironDerived value= age <= 3 ? 7 : (age <= 8 ? 10 : (age <= 13 ? 8 : (age <= 18 ? 11 : 8)))calculated

How It Works

Iron Intake Recommendations

Iron is essential for oxygen transport in the blood. Requirements vary by age and dietary pattern.

RDA for Males

AgeRDA 1-3 years7 mg 4-8 years10 mg 9-13 years8 mg 14-18 years11 mg 19+ years8 mg

Vegetarians need 1.8x more iron because plant-based (non-heme) iron is less readily absorbed.

Worked Example

A 30-year-old omnivore.

age = 30is_vegetarian = 1
  1. 01Age 19+ base iron = 8 mg
  2. 02Omnivore multiplier = 1.0
  3. 03Daily iron = 8 x 1.0 = 8.0 mg
  4. 04Upper limit (adult) = 45 mg

Frequently Asked Questions

Why do vegetarians need more iron?

Plant-based iron (non-heme) is absorbed at a lower rate than animal-based iron (heme). The 1.8x multiplier accounts for this difference.

What are iron-rich foods?

Red meat, poultry, fish, beans, lentils, spinach, fortified cereals, and tofu are all good sources of iron.

What are signs of iron deficiency?

Fatigue, weakness, pale skin, cold hands and feet, brittle nails, and frequent infections are common symptoms.

Ready to run the numbers?

Open Iron Intake Calculator