Unsaturated Iron Binding Capacity (UIBC) Unit Converter

Unsaturated Iron Binding Capacity (UIBC) Unit Converter

Convert UIBC between µg/dL, µg/L and µmol/L, and see the value against the adult reference interval.

Last updated 31 Aug 2026

Unsaturated Iron Binding Capacity (UIBC) converter

Mass ⇄ molar
Ranges are laboratory-specific; confirm against your own report.
42.08µmol/LExample

UIBC 235 µg/dL

Formula and conversion factor

UIBC = TIBC − serum iron
µmol/L = µg/dL × 0.1791
0.1791
from the atomic weight of iron, 55.845 g/mol
UIBC
the binding capacity not currently occupied by iron

Worked example

UIBC 235 µg/dL
235 × 0.1791 = 42.08 µmol/L
If serum iron is 95 µg/dL, TIBC = 95 + 235 = 330 µg/dL

Reference ranges

Measureµg/dLµmol/L
UIBC, adult155 – 35527.8 – 63.6
TIBC, adult240 – 45043.0 – 80.6
Serum iron, adult50 – 1759.0 – 31.3
UIBC is measured directly by many analysers, with TIBC then reported as the sum of UIBC and serum iron.

What UIBC measures

Unsaturated iron binding capacity is the portion of transferrin’s iron-carrying capacity that is currently empty. It is the arithmetic complement of serum iron within TIBC: iron plus UIBC equals TIBC, and most modern analysers actually measure UIBC directly and derive TIBC from it rather than the other way round.

Because it is a derived relationship, UIBC rarely adds information that TIBC and saturation do not already give. It appears on reports mainly as a by-product of how the assay works. Where it is genuinely useful is as a cheap screening test for iron overload: a low UIBC means transferrin is already heavily loaded, and studies of haemochromatosis screening have used UIBC below about 155 µg/dL as a trigger for calculating saturation and measuring ferritin.

In the opposite direction, a high UIBC accompanies iron deficiency, where transferrin is both increased in quantity and poorly occupied. As with every other component of the iron panel, the number is interpreted as part of the pattern rather than alone.

Frequently asked questions

What is the relationship between UIBC, TIBC and serum iron?

TIBC = serum iron + UIBC. If you know any two, the third follows. Most analysers measure serum iron and UIBC and report TIBC as their sum.

Is a low UIBC serious?

It suggests transferrin is heavily saturated, which raises the possibility of iron overload. Calculate transferrin saturation and measure ferritin; a saturation above 45% with a raised ferritin warrants investigation for haemochromatosis.

How do I convert UIBC to µmol/L?

Multiply the µg/dL value by 0.1791, the same factor as serum iron and TIBC, since all three are expressed in terms of iron.

Related calculators

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References

  1. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, iron-binding capacity.
  2. Adams PC et al. Screening for haemochromatosis. Clin Chem.

Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.