Iron deficit calculator
Estimate a total iron deficit with the Ganzoni equation — the classic way to work out how much iron is needed to correct anaemia and refill body stores, from weight and haemoglobin. Haemoglobin in g/dL or g/L.
Your privacy: this calculator runs entirely in your browser — nothing you type is sent anywhere. It's the same on-device principle Quanome is built on.
Educational reference only — not medical advice, and not a dosing tool. Iron repletion (especially intravenous iron) is planned and given by a clinician, who accounts for the cause, the product, and your situation. Ganzoni is a starting estimate, not a prescription.
## The formula
**Ganzoni equation:**
- **Iron deficit (mg) = weight (kg) × (target Hb − current Hb) × 2.4 + iron stores**
- Haemoglobin in g/dL; **iron stores (depot)** are taken as **500 mg** for adults ≥ 35 kg, or **15 mg/kg** below 35 kg (this tool picks the right one from the weight you enter).
- The `× 2.4` factor comes from the iron content of haemoglobin and the blood volume per kg. The depot term is added so stores are refilled, not just the anaemia corrected.
A **default target of 15 g/dL** is used unless you change it. In SI units, enter Hb in g/L and the tool converts (÷ 10) before applying the formula.
## What the number means
The result is a **total milligrams of iron** needed — not a normal range, and only meaningful when haemoglobin is low. In iron-deficiency anaemia the total often lands around **1,000–1,500 mg**. A clinician turns that into an actual plan: which IV iron product, how many infusions, and over what schedule — Ganzoni tends to under-dose, so it's a starting point they adjust.
## The rest of your iron panel
Iron deficit is about *replacing* iron; these tell you whether you're low in the first place:
- **Ferritin** — the best single marker of iron stores; see [what your ferritin level means](/blog/what-your-ferritin-level-means/).
- **Haemoglobin** — the anaemia itself; see [what your haemoglobin level means](/blog/what-your-hemoglobin-level-means/) and [low haemoglobin & anaemia on a CBC](/blog/low-hemoglobin-anemia-what-your-cbc-shows/).
- **Transferrin saturation** — iron in transit; work it out with the [TSAT calculator](/tools/transferrin-saturation-calculator/).
## Track your iron markers over time — privately
A single result is a snapshot; the value is in the **trend**. [Quanome](/) pulls your labs, Apple Health, and even your DNA into one private timeline on your device — parsed locally, never uploaded — with an AI coach that reads your iron panel over time.
Track your iron markers over time, privately
Quanome unifies your labs, Apple Health, and DNA into one private, on-device timeline — with an AI coach. Free on the App Store and Google Play.
Quanome is free on the App Store and Google Play. Want product news too? Leave your email below.
