Daily Iron RDA
18mg
Upper limit: 45mg/day
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The iron intake calculator determines your daily iron requirement based on age, sex, dietary pattern (omnivore vs. vegetarian/vegan), and health status. Iron is an essential mineral required for hemoglobin production — the protein in red blood cells that carries oxygen throughout the body — and for numerous enzymatic reactions involved in energy metabolism and immune function. Iron deficiency is the most common nutritional deficiency worldwide, affecting approximately 2 billion people globally according to the WHO, and iron deficiency anemia affects 25% of the global population. Women of reproductive age have significantly higher iron needs than men due to monthly menstrual blood losses — the RDA is 18mg/day for women 19–50 versus 8mg/day for men. Vegetarians and vegans require approximately 1.8 times more dietary iron than omnivores because plant-based non-heme iron has 2–15% absorption efficiency compared to 15–35% for heme iron from meat. This calculator provides personalized iron targets, identifies the best food sources, and calculates the iron content of common foods with absorption efficiency adjustments for dietary pattern and enhancers/inhibitors (vitamin C enhances; tannins, phytates, calcium inhibit).
RDA Iron: Men 8mg; Women 19-50: 18mg; Pregnant: 27mg; Post-menopause: 8mg Vegetarian Adjustment: RDA × 1.8 Absorption: Heme iron 15-35%; Non-heme iron 2-15% Vitamin C Enhancement: 3× absorption when consumed with non-heme iron
- 1Step 1: Select your age, sex, and whether pregnant or breastfeeding.
- 2Step 2: Indicate your dietary pattern (omnivore, vegetarian, vegan).
- 3Step 3: The calculator applies your RDA with vegetarian adjustment if applicable.
- 4Step 4: Log your food sources and the calculator totals iron with estimated absorption.
- 5Step 5: Identify iron-absorption inhibitors in your diet (tea, coffee, calcium supplements).
- 6Step 6: Check if you are meeting targets; if consistently short, discuss supplementation with a healthcare provider.
Vegetarian women of reproductive age have very high iron needs. Focus on fortified cereals (18mg per serving), lentils (6.6mg per cup), tofu, and always pair with vitamin C.
Iron needs increase dramatically in pregnancy to support fetal blood development and expanded maternal blood volume. Most prenatal vitamins provide 27mg iron. Deficiency in pregnancy increases preterm birth risk.
A 3oz serving of beef provides 3mg iron (heme, 25% absorbed = 0.75mg absorbed). Most adult men exceed the 8mg RDA easily from diet.
Spinach contains non-heme iron with inhibitory oxalic acid. Vitamin C from OJ converts Fe³⁺ to Fe²⁺, the more absorbable form, tripling effective iron absorption.
Professionals in finance and lending use Iron Intake Calc as part of their standard analytical workflow to verify calculations, reduce arithmetic errors, and produce consistent results that can be documented, audited, and shared with colleagues, clients, or regulatory bodies for compliance purposes.
University professors and instructors incorporate Iron Intake Calc into course materials, homework assignments, and exam preparation resources, allowing students to check manual calculations, build intuition about input-output relationships, and focus on conceptual understanding rather than arithmetic.
Consultants and advisors use Iron Intake Calc to quickly model different scenarios during client meetings, enabling real-time exploration of what-if questions that would otherwise require returning to the office for detailed spreadsheet-based analysis and reporting.
Individual users rely on Iron Intake Calc for personal planning decisions — comparing options, verifying quotes received from service providers, checking third-party calculations, and building confidence that the numbers behind an important decision have been computed correctly and consistently.
Extreme input values
In practice, this edge case requires careful consideration because standard assumptions may not hold. When encountering this scenario in iron intake calculator calculations, practitioners should verify boundary conditions, check for division-by-zero risks, and consider whether the model's assumptions remain valid under these extreme conditions.
Assumption violations
In practice, this edge case requires careful consideration because standard assumptions may not hold. When encountering this scenario in iron intake calculator calculations, practitioners should verify boundary conditions, check for division-by-zero risks, and consider whether the model's assumptions remain valid under these extreme conditions.
Rounding and precision effects
In practice, this edge case requires careful consideration because standard assumptions may not hold. When encountering this scenario in iron intake calculator calculations, practitioners should verify boundary conditions, check for division-by-zero risks, and consider whether the model's assumptions remain valid under these extreme conditions.
| Life Stage | RDA (Omnivore) | Vegetarian Target | UL |
|---|---|---|---|
| Men 19–50 | 8 mg | 14 mg | 45 mg |
| Women 19–50 | 18 mg | 32 mg | 45 mg |
| Pregnant | 27 mg | 49 mg | 45 mg* |
| Breastfeeding | 9 mg | 16 mg | 45 mg |
| Men/Women 51+ | 8 mg | 14 mg | 45 mg |
| Adolescent Girls 14–18 | 15 mg | 27 mg | 45 mg |
| Children 9–13 | 8 mg | 14 mg | 40 mg |
Why do vegetarians need 1.8× more iron?
Plant foods contain only non-heme iron, which is absorbed at 2–15% efficiency. Heme iron (from meat) is absorbed at 15–35% efficiency. The 1.8× multiplier compensates for this lower bioavailability. Iron from plant sources is also more sensitive to inhibitors like phytate (in whole grains) and polyphenols (in tea and coffee).
What are the best plant sources of iron?
In the context of Iron Intake Calc, this depends on the specific inputs, assumptions, and goals of the user. The underlying formula provides a deterministic relationship between inputs and output, but real-world application requires interpreting the result within the broader context of finance and lending practice. Professionals typically cross-reference calculator output with industry benchmarks, historical data, and regulatory requirements. For the most reliable results, ensure inputs are sourced from verified data, understand which assumptions the formula makes, and consider running multiple scenarios to bracket the range of likely outcomes.
How do I know if I'm iron deficient?
In the context of Iron Intake Calc, this depends on the specific inputs, assumptions, and goals of the user. The underlying formula provides a deterministic relationship between inputs and output, but real-world application requires interpreting the result within the broader context of finance and lending practice. Professionals typically cross-reference calculator output with industry benchmarks, historical data, and regulatory requirements. For the most reliable results, ensure inputs are sourced from verified data, understand which assumptions the formula makes, and consider running multiple scenarios to bracket the range of likely outcomes.
Can I take too much iron?
Yes — iron toxicity (hemochromatosis, accidental overdose) is dangerous. The tolerable upper intake level (UL) for adults is 45mg/day from supplements. Iron supplements should not be taken unless a deficiency is confirmed by blood test. Excess iron generates free radicals and damages organs. Keep supplements away from children — iron overdose is a leading cause of pediatric poisoning deaths.
Does cooking affect iron content of food?
In the context of Iron Intake Calc, this depends on the specific inputs, assumptions, and goals of the user. The underlying formula provides a deterministic relationship between inputs and output, but real-world application requires interpreting the result within the broader context of finance and lending practice. Professionals typically cross-reference calculator output with industry benchmarks, historical data, and regulatory requirements. For the most reliable results, ensure inputs are sourced from verified data, understand which assumptions the formula makes, and consider running multiple scenarios to bracket the range of likely outcomes.
What inhibits iron absorption?
In the context of Iron Intake Calc, this depends on the specific inputs, assumptions, and goals of the user. The underlying formula provides a deterministic relationship between inputs and output, but real-world application requires interpreting the result within the broader context of finance and lending practice. Professionals typically cross-reference calculator output with industry benchmarks, historical data, and regulatory requirements. For the most reliable results, ensure inputs are sourced from verified data, understand which assumptions the formula makes, and consider running multiple scenarios to bracket the range of likely outcomes.
Is iron supplementation appropriate during pregnancy?
In the context of Iron Intake Calc, this depends on the specific inputs, assumptions, and goals of the user. The underlying formula provides a deterministic relationship between inputs and output, but real-world application requires interpreting the result within the broader context of finance and lending practice. Professionals typically cross-reference calculator output with industry benchmarks, historical data, and regulatory requirements. For the most reliable results, ensure inputs are sourced from verified data, understand which assumptions the formula makes, and consider running multiple scenarios to bracket the range of likely outcomes.
プロのヒント
If you need to boost iron absorption from plant foods without supplements, pair every iron-rich meal with a vitamin C source — squeeze lemon over lentils, add bell peppers to tofu stir-fry, eat kiwi with iron-fortified cereal. This simple habit can double to triple your actual absorbed iron.
ご存知でしたか？
The discovery that iron deficiency causes cognitive impairment in children led to global food fortification programs. Flour iron fortification, implemented in 80+ countries, has prevented an estimated 10 million cases of iron deficiency anemia annually. In the US, iron-fortified cereals are the largest single dietary source of iron for most adults.