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Iron Deficiency Calculator

Health

Estimate total body iron deficit using the Ganzoni formula from body weight, current and target hemoglobin, and iron stores instantly and free.

Reviewed by the thecalcu.com team · Last updated July 19, 2026

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Estimated Total Iron Deficit

1,436

This calculator computes your Estimated Total Iron Deficit from the values you enter.

Inputs
Body WeightTarget HemoglobinCurrent HemoglobinIron Stores Reserve
Outputs
Estimated Total Iron Deficit

What is a Iron Deficit?

The Iron Deficiency Calculator estimates total body iron deficit using the Ganzoni formula, from body weight, the gap between current and target hemoglobin, and an iron stores allowance. This is an educational reference tool, not a dosing calculator for actual treatment.

For a related iron status calculation, see the Transferrin Saturation Calculator.

Why Use an Iron Deficiency Calculator?

The Ganzoni formula is a widely referenced equation in hematology literature, and this calculator lets you explore how body weight and hemoglobin deficit combine to produce an estimated total iron deficit figure.

Who Should Use This Calculator?

  • Students of hematology or pharmacy learning how the Ganzoni formula is structured.
  • Healthcare educators demonstrating iron deficit estimation methodology.
  • Researchers working with iron replacement reference literature.
  • Anyone curious about how body weight and hemoglobin combine in this classic formula.

What Insights Does the Iron Deficiency Calculator Give You?

The Estimated Total Iron Deficit in milligrams is the sole output, combining the weight-and-hemoglobin-based correction component with the iron stores allowance. This is an educational estimate, actual treatment dosing must be determined by a qualified healthcare professional.

How to use this Iron Deficit calculator

  1. Enter the body weight in kilograms.
  2. Enter the target hemoglobin value.
  3. Enter the current hemoglobin value.
  4. Adjust the iron stores reserve allowance if needed (default 500 mg).
  5. Read the Estimated Total Iron Deficit instantly.
  6. Remember this is an educational reference only, actual treatment decisions require a qualified healthcare professional.
Show formula & methodology ↓Show less ↑

Formula & Methodology

Total Iron Deficit (mg) = Body Weight (kg) × (Target Hb − Current Hb) × 2.4 + Iron Stores (mg)

Worked example, a 65 kg patient with a target hemoglobin of 15 g/dL, current hemoglobin of 9 g/dL, and 500 mg iron stores allowance:

Total Iron Deficit = 65 × (15 − 9) × 2.4 + 500 = 65 × 6 × 2.4 + 500 = 936 + 500 = 1,436 mg

Frequently Asked Questions

What is the Ganzoni formula?
The Ganzoni formula is a commonly referenced equation for estimating total body iron deficit from body weight, the gap between current and target hemoglobin, and an allowance for iron stores, often cited in discussions of intravenous iron replacement.
How is total iron deficit calculated?
The formula multiplies body weight by the hemoglobin deficit (target minus current) and a constant of 2.4, then adds an iron stores allowance (commonly 500 mg) to account for replenishing the body's iron reserves.
What does the constant 2.4 represent?
The 2.4 constant in the Ganzoni formula reflects blood volume and iron content assumptions used to convert a hemoglobin deficit into an equivalent iron mass requirement.
Is this calculator a dosing tool for IV iron treatment?
No, this is an educational reference calculator only. Actual iron replacement therapy dosing must be determined by a qualified healthcare professional based on the complete clinical picture, not a general online calculator.
What is a typical iron stores allowance used in this formula?
500 mg is a commonly cited default iron stores allowance in the Ganzoni formula, representing the reserve replenishment component beyond correcting the immediate hemoglobin deficit, though specific clinical protocols may use different figures.
Why does target hemoglobin matter in this calculation?
The formula is built around the gap between current and target hemoglobin, since a larger gap implies a greater estimated iron deficit needing correction.
Does this calculator account for ongoing blood loss?
No, this calculator estimates a static iron deficit based on the entered values only. Ongoing blood loss or other factors affecting iron balance would need to be considered separately by a treating physician.
How does this relate to the Transferrin Saturation Calculator?
The [Transferrin Saturation Calculator](/transferrin-saturation-calculator/) assesses current iron status from serum iron and TIBC, while this calculator estimates the total deficit that might need correcting, both are related iron-status reference calculations.
What units does this calculator use?
This calculator uses kilograms for body weight, g/dL for hemoglobin, and milligrams for iron deficit and iron stores, matching standard units used in the Ganzoni formula.
Who developed the Ganzoni formula?
The Ganzoni formula has been widely referenced in hematology literature for decades as a standard method for estimating total iron deficit in the context of iron replacement discussions.
Also known as
Ganzoni formula calculatortotal iron deficit calculatorIV iron dosing referenceiron replacement formula