Total Iron-Binding Capacity Calculator

How it is calculated

There are two modes. In the default mode the tool adds serum iron and UIBC (unsaturated iron-binding capacity), both in µg/dL: TIBC = iron + UIBC. In transferrin mode it estimates TIBC = 1.25 × transferrin, with transferrin in mg/dL, and derives UIBC as TIBC − iron. Transferrin saturation is then iron ÷ TIBC × 100. The tool labels TIBC below 250 µg/dL as low, 250 to 450 as within the usual range and above 450 as high, and quotes a saturation reference of 20 to 50%. Results are rounded to whole µg/dL. TIBC must be positive, and serum iron cannot exceed TIBC (saturation above 100% is impossible), so such inputs give no result; transferrin mode also needs a transferrin value above zero. Labs may use other reference ranges and units, so check yours.

Common mistakes

• Choosing the transferrin method but typing the lab's UIBC value, or the other way round. A UIBC of 250 read as transferrin gives a TIBC of 312.5 and a UIBC of about 233, not what the lab reported.
• Entering transferrin in g/L. The formula expects mg/dL, so 2.6 g/L must be entered as 260; typing 2.6 gives a TIBC of about 3 and, because iron then exceeds it, no result.
• Mixing units: iron in µmol/L together with UIBC in µg/dL gives a meaningless sum, since all values must be µg/dL.
• Entering a serum iron larger than the TIBC (for example iron 400 with transferrin 264, which gives a TIBC of 330). The tool rejects it and shows no result instead of a saturation above 100%.
• Reading a low saturation as a diagnosis. The tool only labels the numbers and cannot tell the cause.