Last updated October 13, 2026 · Report an error
Iron travels through the bloodstream bound to a transport protein called transferrin, and Transferrin Saturation (TSAT%) measures what percentage of that transferrin's total iron-carrying capacity is actually occupied by iron at a given moment. It's calculated as TSAT% = (serum iron ÷ TIBC) × 100, where TIBC (Total Iron-Binding Capacity) reflects how much iron all the transferrin in the blood could carry if fully saturated, and serum iron reflects how much iron is actually bound right now. TSAT is one of the standard measurements included in an "iron studies" or "iron panel" blood test, typically ordered alongside serum iron, TIBC, and ferritin together when investigating suspected iron deficiency, iron overload, or unexplained anemia. The commonly cited normal reference range for TSAT in adults is roughly 20-50%, though — like most lab reference ranges — the exact cutoffs can vary slightly between laboratories. This calculator performs pure arithmetic on the lab values you provide, for general reference and educational purposes only — it is not a medical diagnosis. Consult a doctor for actual interpretation of iron studies.
How it works
Enter serum iron and total iron-binding capacity (TIBC), both from the same iron studies panel and in the same units (typically µg/dL). The tool divides serum iron by TIBC and multiplies the result by 100 to express transferrin saturation as a percentage.
- Enter serum iron (ug/dL).
- Enter tIBC (ug/dL).
- Click Calculate to see your results.
Examples
A typical normal result
Serum iron 90, TIBC 300: TSAT = (90/300) x 100 = 30% — within the commonly cited normal range of 20-50%.
A low result suggestive of iron deficiency
Serum iron 30, TIBC 450: TSAT = (30/450) x 100 ≈ 6.7% — well below the commonly cited normal range, a pattern commonly associated with iron deficiency (low iron, often with a compensatory high TIBC).
A high result suggestive of iron overload
Serum iron 180, TIBC 250: TSAT = (180/250) x 100 = 72% — well above the commonly cited normal range, a pattern commonly associated with iron overload conditions.
Who should use it
- Reviewing an iron studies panel.
- Iron deficiency and iron overload education.
- Understanding the relationship between serum iron, TIBC, and TSAT in a hematology course.
Industry applications
- Hematology reference
- Clinical education
Advantages
- Simple, standard formula.
- Quick reference against a normal range.
- Widely used, well-established lab calculation.
Limitations
- Reference ranges vary slightly by lab.
- Does not replace clinical interpretation of the full iron panel (including ferritin).
Common mistakes to avoid
- Entering serum iron and TIBC in different units.
- Interpreting TSAT alone without considering ferritin and the broader clinical picture.
- Assuming a single TSAT reading, rather than a trend or repeat test, definitively confirms a diagnosis.
Best practices
- Use serum iron and TIBC from the same blood draw/report.
- Review TSAT alongside ferritin and the full iron panel rather than as a standalone number.
- Discuss any abnormal TSAT result with a doctor, since both low and high values warrant different follow-up investigations.
Tips
- TSAT is typically interpreted alongside ferritin and TIBC together, not as a standalone value, per standard hematology teaching.
- A trend across multiple readings is often more clinically useful than a single isolated value.