Iron Deficit Calculator

The Iron Deficit Calculator estimates total elemental iron requirement based on body weight, hemoglobin levels, and iron stores using the Ganzoni formula. This tool helps healthcare providers determine the estimated dosage needed to treat iron deficiency anemia effectively. Whether you're planning an IV iron infusion or calculating oral supplementation needs, this tool provides a precise deficit estimate to guide clinical decisions.

Patient's current body weight (10 - 250 kg).
Measured hemoglobin concentration (3.0 - 18.0 g/dL).
Desired hemoglobin level for correction (Must be > Current).
Standard amount to replenish stores (Default 500mg).

Understanding the Ganzoni formula is essential for appropriate iron replacement therapy. This calculator simplifies the process by accounting for individual patient physiology and storage needs.

How Total Iron Deficit Is Calculated

Iron Deficit = Weight × (Target Hb − Current Hb) × 2.4 + Iron Stores

Where:

  • Weight: Patient's body weight in kilograms.
  • Target & Current Hb: Desired and measured hemoglobin in g/dL.
  • 2.4: Conversion factor accounting for blood volume and hemoglobin iron content.
  • Iron Stores: Additional amount (usually 500mg) to replenish depleted ferritin levels.

The calculation begins by finding the difference between the target and current hemoglobin levels. This deficit is multiplied by the body weight and a factor of 2.4, which estimates the amount of iron needed to generate new hemoglobin in the blood. Finally, a standard storage replacement value is added to ensure the patient has sufficient iron reserves after treatment.

This method, known as the Ganzoni formula, is widely accepted in hematology because it provides a personalized estimate rather than a flat dosage, improving safety and efficacy.

What Your Iron Deficit Means

The calculated value represents the total amount of elemental iron required to correct the anemia and replenish stores. Clinicians use this total to determine the number of IV iron infusions or the duration of oral supplementation.

Total Deficit Range Clinical Context
< 500 mg Mild deficiency; often treatable with oral iron or a single low-dose IV infusion.
500 - 1000 mg Moderate deficiency; typically requires 1-2 IV infusions or extended oral therapy.
> 1000 mg Severe deficiency; usually requires multiple high-dose IV infusions to replete fully.

Clinical Note

Always round the calculated dose to the nearest available vial size when prescribing IV iron. Do not exceed the maximum single dose recommended for the specific iron product being used.

Related Calculators

Calculation logic verified using publicly available standards.

View our Accuracy & Reliability Framework →