Transferrin Calculator — TIBC & Transferrin Saturation
Convert a serum transferrin level (mg/dL) to an estimated TIBC (µg/dL) and calculate transferrin saturation from serum iron — two key iron-status markers used to distinguish iron-deficiency anaemia from iron overload and anaemia of chronic disease.
mg/dL
µg/dL
TIBC ≈ Transferrin (mg/dL) × 1.25
- 1
Serum transferrin
280Each mg/dL of transferrin provides approximately 1.25 µg/dL of iron-binding capacity. - 2
Estimated TIBC
280 × 1.25 = 350
How does this calculator work?
Estimated TIBC ≈ Transferrin (mg/dL) × 1.25 µg/dL. Transferrin saturation = serum iron ÷ TIBC × 100%. Normal saturation: 20–45 %; < 16 % suggests iron deficiency; > 45 % raises concern for iron overload. For example, transferrin 280 mg/dL → TIBC 350 µg/dL; serum iron 100 µg/dL → 29 % saturation (normal). Always confirm with ferritin and full blood count.
Formula
How this is calculated
Transferrin is a glycoprotein produced by the liver that transports iron in the blood. Each transferrin molecule can bind two iron atoms. The total iron-binding capacity (TIBC) measures the maximum amount of iron the blood could carry if all transferrin were fully saturated — it reflects the functional reserve of transferrin. Because TIBC is almost entirely determined by the transferrin concentration, it can be estimated from the transferrin level using the approximate conversion factor of 1.25 µg/dL TIBC per mg/dL transferrin (derived from transferrin's molecular weight of ~79 500 Da and its 2-iron binding capacity).
Transferrin saturation (%) = serum iron ÷ TIBC × 100. A saturation below 16 % combined with low ferritin and low haemoglobin is classic iron-deficiency anaemia. A saturation above 45–50 % — especially with elevated ferritin — raises concern for hereditary haemochromatosis or transfusional iron overload. In anaemia of chronic disease (ACD), saturation is typically low-normal but ferritin is elevated, helping distinguish ACD from true iron deficiency.
The UIBC (unsaturated or latent iron-binding capacity = TIBC − serum iron) represents the spare binding sites on transferrin — i.e., how much additional iron the blood could absorb. Reference ranges quoted here are approximate adult values; paediatric, pregnancy, and elderly ranges differ. Laboratory methods (immunoturbidimetry vs. immunonephelometry) and the conversion factor used can vary slightly between institutions — always interpret results in their clinical context.
Frequently asked questions
Transferrin is the actual protein measured in blood. TIBC is a functional assay measuring the maximum iron the blood can bind — it mainly reflects transferrin, so the two track closely. Many modern labs report transferrin directly rather than measuring TIBC with the older colorimetric method; either can be converted to the other using the ≈1.25 factor.
Saturation above 45–50 % can indicate excess iron delivery to tissues. Combined with elevated ferritin (> 200–300 µg/L), it suggests hereditary haemochromatosis, excessive iron supplementation, or repeated blood transfusions. Confirmatory genetic testing (HFE mutations C282Y, H63D) is usually ordered if haemochromatosis is suspected.
Yes. To convert: serum iron µmol/L × 5.585 = µg/dL; transferrin g/L × 100 = mg/dL. In SI units, TIBC (µmol/L) ≈ Transferrin (g/L) × 20.1, and saturation (%) = iron (µmol/L) / TIBC (µmol/L) × 100. This calculator uses conventional US units (µg/dL, mg/dL); adjust inputs if your lab reports SI values.
Also known as
TG we-Calculate Editorial Team. (2026). Transferrin Calculator — TIBC & Transferrin Saturation [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/transferrin-calculator
TG we-Calculate Editorial Team. "Transferrin Calculator — TIBC & Transferrin Saturation." TG we-Calculate. 2026. https://we-calculate.com/calculator/transferrin-calculator.
TG we-Calculate Editorial Team, "Transferrin Calculator — TIBC & Transferrin Saturation," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/transferrin-calculator
@misc{wecalculate_transferrin_calculator, title = {Transferrin Calculator — TIBC & Transferrin Saturation}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/transferrin-calculator}}, year = {2026}, note = {TG we-Calculate} }
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