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Transferrin Saturation Calculator

Find transferrin saturation (TSAT).

How it is calculated

The tool computes TSAT = serum iron / TIBC × 100. serum iron is the iron concentration in the blood sample and TIBC is the total iron-binding capacity from the same panel. The result is a percentage with two decimals. It is a plain ratio, so the tool does not convert units: both values must be in the same unit, for example µg/dL for both or µmol/L for both.

TIBC must be greater than zero and the iron value cannot be negative; otherwise there is no result. The tool does not check whether the entered values are physiologically plausible, and it does not interpret the percentage. What counts as low or high depends on the laboratory and on the clinical picture, so results should be discussed with a clinician.

Worked example

A lab report lists serum iron 85 µg/dL and TIBC 310 µg/dL. Divide iron by capacity: 85 / 310 = 0.2742. Multiply by 100 to get the percentage: 27.42%. This means about 27% of the binding sites on transferrin are occupied by iron in that sample.

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Common mistakes

  • Using iron in µmol/L and TIBC in µg/dL (or the reverse); the ratio is meaningless unless both use the same unit.
  • Entering UIBC (unsaturated iron-binding capacity) instead of TIBC; TIBC is roughly iron plus UIBC, so UIBC alone gives a TSAT that is far too high.
  • Entering transferrin in mg/dL in the TIBC field; transferrin and TIBC are related but not the same number.
  • Comparing a result with a reference range from a different laboratory or method without checking; ranges differ between labs.
  • Interpreting TSAT without ferritin and the clinical context, since inflammation and liver disease can change TIBC and shift the percentage.

Sources

About this calculator

Transferrin saturation is calculated as TSAT = (serum iron / total iron-binding capacity) × 100, expressing what fraction of the blood's iron-carrying protein, transferrin, is actually loaded with iron rather than running empty. TIBC indirectly measures how much transferrin is circulating, so the ratio reflects iron availability independent of how much transferrin the liver happens to be producing.

Hematologists and primary care physicians order this alongside serum ferritin as part of an iron studies panel, since a low TSAT points toward iron deficiency while a persistently elevated TSAT — typically above 45% — is one of the earliest markers used to screen for hereditary hemochromatosis, an iron-overload disorder. Because acute inflammation and liver disease also shift TIBC, clinicians interpret the ratio alongside ferritin and clinical context rather than in isolation.

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  • Editorial team

    The percentage is only as comparable as the two measurements behind it: iron and TIBC must come from the same blood sample and the same unit, and the reference range printed on your own lab report is the one to compare against, since ranges differ between labs. For example, 80 over 320 gives 25.00 percent. Serum iron can vary during the day, so discuss results with your doctor. Which other iron panel figures would you like to calculate?

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