What is the Ganzoni formula?

The Ganzoni formula calculates total iron deficit as: Iron Deficit (mg) = Body Weight (kg) × (Target Hb − Actual Hb) × 2.4 + 500 mg (for iron stores). The constant 2.4 derives from blood volume (70 mL/kg), hemoglobin iron content (0.34%), and a unit conversion factor.

What target hemoglobin should I use?

For most non-pregnant adults the standard target is 15 g/dL. For patients with heart failure or chronic kidney disease, clinicians sometimes use a lower target (e.g. 12–13 g/dL). Always follow your institution's protocol and clinical judgment.

Is this calculator suitable for children or pregnant women?

The classic Ganzoni formula uses a fixed iron store add-on of 500 mg suited for average adults. Modified versions exist for children (reduced store allowance) and pregnant women. Consult specialist guidelines before applying this tool to those populations.

How accurate is the Ganzoni formula?

The Ganzoni formula is a widely cited clinical estimate, but it tends to underestimate the true iron deficit in severely depleted patients. Treat the result as a starting-point dose; reassess hemoglobin and ferritin after therapy.

What do the vial estimates mean?

The tool shows how many standard vials of common IV iron products would cover the calculated deficit. These are rough guides only — actual dosing, maximum single-dose limits, and infusion schedules must be confirmed in the product monograph and with a pharmacist.

Does this tool store my patient data?

No. All calculations happen entirely in your browser. No data is sent to any server, and nothing is stored after you close or refresh the page.

Iron Deficit Calculator (Ganzoni Formula)

Name: Iron Deficit Calculator (Ganzoni Formula)
Availability: InStock
Author: Nham Vu

Calculate total body iron deficit (in mg) using the Ganzoni formula for guiding IV iron therapy in iron deficiency anemia.

Patient Parameters

Body Weight

Use actual body weight (not ideal body weight).

Actual Hemoglobin (g/dL)

Patient's current measured hemoglobin.

Target Hemoglobin (g/dL)

Typically 15 g/dL for non-pregnant adults.

Iron Store Replenishment (mg)

Standard is 500 mg for adults; some guidelines use 0 mg.

Enter patient parameters and click
Calculate Iron Deficit to see results.

Summary

Calculate total body iron deficit (in mg) using the Ganzoni formula for guiding IV iron therapy in iron deficiency anemia.

How it works

Enter the patient's body weight in kilograms (or pounds — the tool converts automatically).
Enter the patient's current (actual) hemoglobin in g/dL.
Enter the desired target hemoglobin in g/dL (typically 15 g/dL for adults).
The tool applies the Ganzoni formula: Iron Deficit (mg) = Weight (kg) × (Target Hb − Actual Hb) × 2.4 + 500.
Results show total iron deficit in mg along with typical vial counts for common IV iron preparations.

Use cases

Determining cumulative IV iron dose for patients with iron deficiency anemia.
Pre-operative anemia optimization to reduce transfusion risk.
Dosing guidance for iron sucrose, ferric carboxymaltose, or low-molecular-weight iron dextran.
Teaching medical students and residents the Ganzoni formula.
Quickly estimating iron repletion needs during ward rounds.
Cross-checking manually calculated IV iron prescriptions.
Supporting pharmacist review of iron replacement orders.
Screening patients for single-dose versus multi-dose iron therapy regimens.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu