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Estimate your total elemental iron requirement based on body weight and the difference between current and target hemoglobin.
Ganzoni arithmetic for total iron deficit with prescribed target Hb/storage iron. UK Venofer label is the reference, not a route, schedule or single-dose recommendation. Reference
Enter prescribed storage iron. The UK Venofer label example uses 500mg at body weight >=35kg; this is not a general personal recommendation.
Enter your weight and current hemoglobin to estimate your iron deficit
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
This calculator applies the Ganzoni equation to estimate a total iron deficit in milligrams from four values: body weight, current hemoglobin, a target hemoglobin, and an iron-stores allowance. The result is an arithmetic estimate based on those entries. It does not determine whether someone has iron deficiency or how to treat it.
Hemoglobin (Hb) is the oxygen-carrying protein measured on a blood test. The equation combines an Hb-gap component with the storage-iron amount entered separately. That second amount is not automatically selected here: use only a value specified for the calculation by a qualified clinician. The UK Venofer product information documents this equation, but its product instructions do not establish a US treatment plan.
Total iron deficit (mg) = weight (kg) × [target Hb − current Hb] (g/dL) × 2.4 + iron-stores allowance (mg)
For example, with 60 kg, current Hb 9.0 g/dL, target Hb 13.0 g/dL, and an entered storage allowance of 500 mg, the Hb difference is 4.0 g/dL. The Hb component is 60 × 4.0 × 2.4 = 576 mg; adding 500 mg gives a total of 1,076 mg. These figures illustrate the arithmetic only. In the tool, the Hb component and total are rounded to the nearest whole milligram for display, while the storage amount is shown as entered.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Enter body weight in kilograms. If your source gives pounds, convert the value to kilograms before entering it; the field is not labeled for pounds.
Enter current hemoglobin in g/dL, then enter the target hemoglobin in g/dL. Check the units printed on the lab report. A value in g/L must be divided by 10 before entry; for instance, 90 g/L is 9.0 g/dL.
Enter the prescribed iron-stores allowance in milligrams. The target and allowance fields are required inputs, not universal defaults. The calculator accepts weight from 1 to 300 kg, current Hb from 2 to 20 g/dL, target Hb from 8 to 18 g/dL, and an allowance from 0 to 1,000 mg. The target must be higher than current Hb.
Review the total alongside its two displayed parts: iron associated with the Hb difference and the entered stores allowance. Use the copy control if helpful, and keep the original inputs with the result so the arithmetic can be checked.
Use cases
See how the tool fits into real work and everyday tasks.
If a clinician has already chosen the target Hb and storage allowance, enter those same assumptions to see how they combine with the recorded weight and current Hb. Bring any difference between this result and a treatment plan back to the clinician for review.
For education, change one value at a time while keeping the others fixed. A larger Hb gap or body weight increases the Hb component; changing the storage allowance changes the total by the same number of milligrams. This illustrates the equation without establishing an appropriate target or allowance for a person.
Q&A
Find concise answers to common questions and confusing cases.
Convert it to g/dL first. Divide g/L by 10; for example, 90 g/L becomes 9.0 g/dL. Entering 90 into a g/dL field would be outside the accepted range and would not represent the same value.
All four fields must contain valid numbers within their accepted ranges, and target Hb must be greater than current Hb. Check for a missing field, a unit mismatch, or a target that is equal to or below the current value.
No. The target Hb and iron-stores allowance are required entries. Use the values selected for the specific calculation by a qualified clinician; do not treat example values from a product document or another website as personal defaults.
No. It is a calculated total deficit, not a daily oral amount, a single infusion amount, or a schedule. Product-specific dosing and the decision to use oral or intravenous iron require clinical assessment and the applicable prescribing information.
Notes
Review scope, result limitations, and important precautions before use.
This calculator performs the Ganzoni arithmetic using the values entered. It cannot diagnose iron deficiency or anemia, assess the cause of an abnormal blood count, decide whether iron is needed, or select a treatment. The formula reference linked above is the UK Venofer product information; it must not be read as current US labeling or as a recommendation for a US product.
Do not use the result to choose an oral dose, an intravenous product, a route, an amount per administration, or a treatment interval. Those decisions depend on clinical findings, laboratory assessment, the specific product information, and the treating professional’s judgment. If you are checking a result for yourself, ask your healthcare professional to confirm the inputs and interpret the estimate.
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