We use cookies.This website uses essential cookies to operate core features. With your consent, we also use analytics cookies to understand traffic and improve the service. For more details, see our .
We use cookies.This website uses essential cookies to operate core features. With your consent, we also use analytics cookies to understand traffic and improve the service. For more details, see our .
Iron Deficit Calculator
If this tool helped you, you can buy us a coffee ☕
Estimate your total elemental iron requirement based on body weight and the difference between current and target hemoglobin.
A 500 mg iron stores allowance is commonly used for adults. A clinician should adjust this amount for children, people with low body weight, and other special circumstances.
Enter your weight and current hemoglobin to estimate your iron deficit
Fetal Weight Calculator
Quickly estimate fetal weight using ultrasound data like Biparietal Diameter (BPD), Abdominal Circumference (AC), and Femur Length (FL). Uses the Hadlock formula to provide a reliable reference for pregnancy assessment.
BMR Calculator (Basal Metabolic Rate)
Calculate the minimum daily calories your body needs at rest based on gender, height, weight, and age. Get a scientific reference for your diet and fitness plans.
Creatinine Clearance Calculator
Enter your age, weight, and serum creatinine to quickly assess your kidney function.
For an adult who weighs 60 kg and has a current hemoglobin level of 90 g/L, setting a target hemoglobin of 130 g/L and iron stores of 500 mg produces an estimated total iron deficit of about 1,077 mg.
This result helps explain approximately how much elemental iron may be needed to correct the hemoglobin deficit and replenish iron stores. It is most useful in the following situations:
This is not a dietary iron intake calculator. It cannot determine how many oral iron tablets to take per day or how much intravenous iron to receive in a single infusion.
This calculator estimates the total iron deficit, expressed in milligrams (mg) of elemental iron. It uses the widely referenced Ganzoni formula: first estimating the iron needed to raise hemoglobin to the target level, then adding the amount required to replenish iron stores.
Iron requirement (mg) = body weight (kg) × [target hemoglobin − current hemoglobin] (g/L) × 0.24 + iron stores (mg)
The 0.24 factor accounts for blood volume and the iron content of hemoglobin. A higher body weight or larger hemoglobin deficit generally produces a higher estimate. Even when the current hemoglobin is close to the target, the result may remain above zero if iron stores are included.
Using these values in the formula:
Hemoglobin deficit = 130 − 90 = 40 g/L
Iron needed to correct hemoglobin = 60 × 40 × 0.24 = 576 mg
Total iron requirement = 576 + 500 = 1,076 mg. Depending on the calculator's display precision, this may appear as approximately 1,076 mg or 1,077 mg.
This represents an estimated total elemental iron deficit of about 1.08 g. It is not a daily dose and does not mean that 1,076 mg can be administered in a single intravenous infusion. The product, maximum single dose, number of infusions, and follow-up schedule must be determined from the prescribing information and your clinician's instructions.
The result has two components: the iron needed to correct the hemoglobin deficit and the iron needed to replenish stores. A higher result only means that the formula estimates a larger total deficit. It cannot determine the cause or severity of anemia by itself.
| Result | Possible meaning | Next step |
|---|---|---|
| The target is above the current level, and the result is substantially higher than the iron stores value | The hemoglobin deficit accounts for a significant share of the iron requirement | Review ferritin, transferrin saturation, and the possible underlying cause |
| The result is close to the iron stores value | Current hemoglobin is near the target, so most of the estimate comes from replenishing stores | Confirm whether replenishing iron stores is clinically indicated |
| The target equals the current level | The hemoglobin-deficit component is 0 | The result comes entirely from the entered iron stores value |
| The target is below the current level | The values may have been reversed, producing an invalid or unexpected result | Check the lab report, units, and input fields |
Comparison example 1: For the same 60 kg adult, increase current hemoglobin to 120 g/L while keeping the target at 130 g/L and iron stores at 500 mg. The result is 60 × (130 − 120) × 0.24 + 500 = 644 mg. Compared with the main example, the smaller hemoglobin deficit reduces the estimated total requirement.
Boundary example: If body weight is 40 kg, both current and target hemoglobin are 130 g/L, and iron stores are set to 0 mg, the result is 40 × 0 × 0.24 + 0 = 0 mg. This only means the formula detected no deficit. It does not rule out early iron deficiency or other types of anemia.
This result is intended only to help explain the Ganzoni formula. It cannot replace a diagnosis, prescription, or product-specific prescribing information. The estimate depends on body weight, hemoglobin measurement, and the selected target. Scale inaccuracies, timing of blood collection, dehydration, and blood dilution or concentration caused by fluid therapy can all affect the result. Newborns, children, pregnant or postpartum patients, and people with kidney impairment, heart failure, cancer treatment, active bleeding, a recent transfusion, or a risk of iron overload require specialist assessment and condition-specific protocols.
Intravenous iron can cause infusion reactions or severe allergic reactions and must be assessed and monitored in a medical setting. Oral iron may cause nausea, abdominal pain, constipation, or dark stools. Iron overdose can cause poisoning and is especially dangerous when accidentally ingested by children. Seek prompt medical care for chest pain, difficulty breathing, fainting, persistent palpitations, severe weakness, or active bleeding. Do not wait for a calculator result.
1. If the result is 1,000 mg, does that mean I should take 1,000 mg of iron every day?
No. This tool estimates the total elemental iron deficit, not a daily dose. Oral and intravenous products differ in absorption, elemental iron content, and maximum dosing limits. A clinician should determine your treatment plan.
2. Can I still be iron deficient if my hemoglobin is normal?
Yes. Iron stores may decline before hemoglobin falls. A normal Hb level does not completely rule out iron deficiency; ferritin, transferrin saturation, inflammation, and other clinical findings must also be considered.
3. Which result should I use for “Current hemoglobin”?
In general, use the most recent reliable complete blood count obtained before the treatment decision. A single result may not be suitable after a recent transfusion, substantial IV fluid administration, significant dehydration, or during ongoing bleeding.
4. Should “Iron stores” always be set to 500 mg?
No. Although 500 mg is a common assumption in adult calculations, a different value may be used for people with lower body weight or certain medical conditions. Whether iron stores need to be replenished also depends on the treatment goal.
5. Should the calculated value be rounded?
The formula result can be rounded to the nearest milligram, but actual dosing depends on product strengths, the maximum single dose, and the treatment schedule. Rounding and divided-dose plans should follow the specific prescribing information and your clinician's instructions.
6. Can this result tell me how severe my anemia is?
No. It only estimates the iron deficit from the entered values. Anemia severity is assessed mainly from hemoglobin levels and symptoms, while the cause requires other complete blood count indices, iron studies, and clinical evaluation. Enter your lab values in the calculator above, then ask your clinician to review the result.
