UIBC Calculator (Unsaturated Iron-Binding Capacity)
Calculate Unsaturated Iron-Binding Capacity (UIBC) from your Total Iron-Binding Capacity (TIBC) and serum iron values.
All fields share one unit — changing it on any field updates the others automatically.
Your Calculated Result
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Calculation
UIBC = TIBC − Serum Iron
This calculator is provided for general informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional to interpret your lab results.
What is UIBC?
Unsaturated iron-binding capacity (UIBC) measures how much of transferrin’s iron-carrying capacity is still empty.
Transferrin is the protein in blood that transports iron — normally only about a third of it is carrying iron at any time, leaving roughly two-thirds unsaturated and available.
UIBC quantifies that unused portion. Combined with serum iron, it makes up total iron-binding capacity (TIBC): TIBC = Serum Iron + UIBC.
UIBC & TIBC Formula
| Calculation | Formula |
| Find UIBC | UIBC = TIBC − Serum Iron |
| Find TIBC | TIBC = Serum Iron + UIBC |
Both values are typically reported in µg/dL, and can be converted to µmol/L using a standard conversion factor (1 µg/dL ≈ 0.1791 µmol/L).
Once you have TIBC, you can calculate transferrin saturation (TSAT) with our TSAT Calculator.
Calculation Example
Suppose a lab report shows:
- TIBC = 400 µg/dL
- Serum Iron = 100 µg/dL
UIBC = 400 − 100 = 300 µg/dL
This means 300 µg/dL of transferrin’s binding capacity is currently unoccupied and available to carry additional iron.
| Test | Typical Adult Range |
| TIBC | 250–450 µg/dL |
| UIBC | 120–300 µg/dL |
| Serum Iron | 60–170 µg/dL (men), 50–150 µg/dL (women) |
Reference ranges vary somewhat between laboratories depending on the assay method used, so always compare your result against the range printed on your own lab report.
What High or Low UIBC Can Indicate
According to clinical references, TIBC and UIBC typically rise together in iron-deficiency anemia, since the body increases transferrin production to maximize iron transport when supply is low. Conversely, iron overload conditions and some chronic diseases are associated with a reduced UIBC, since more of transferrin’s capacity is already occupied by iron.
If UIBC is high and TSAT is low, you may need to calculate your total iron deficit to plan replacement.
UIBC is not interpreted in isolation — it’s one part of a full iron panel, usually read alongside serum iron, TIBC, transferrin saturation (TSAT), and ferritin, since several of these can shift for reasons unrelated to iron status (such as pregnancy, oral contraceptive use, or inflammation).
How UIBC Relates to TIBC and TSAT
- TIBC is the total capacity of transferrin to bind iron (bound + unbound iron capacity combined).
- UIBC is just the unbound portion of that total.
- TSAT (transferrin saturation) is calculated using serum iron and TIBC together — UIBC feeds into that same picture, since TIBC is derived from it.
If you already have your TSAT or need to calculate it separately, use our TSAT Calculator.
Frequently Asked Questions
How to calculate unsaturated iron-binding capacity?
UIBC is calculated by subtracting serum iron from total iron-binding capacity (TIBC): UIBC = TIBC − Serum Iron.
Both values come from the same iron panel blood test, so if your lab report includes TIBC and serum iron, you can find UIBC directly using our calculator above.
What is the normal range for unsaturated iron-binding capacity?
UIBC typically falls between 120–300 µg/dL in adults, though exact cutoffs vary somewhat by laboratory and testing method.
Always compare your result against the reference range printed on your own lab report, since different labs calibrate their assays slightly differently.
What to do if UIBC is high?
A high UIBC often points toward iron deficiency, since transferrin has more empty capacity when there’s less iron in circulation to fill it. However, UIBC is only one part of a full iron panel and isn’t diagnostic on its own — the appropriate next step is to discuss the result with a doctor, who will typically look at it alongside serum iron, TIBC, ferritin, and transferrin saturation before making any determination.
How is TIBC calculated?
TIBC is calculated by adding serum iron and UIBC together: TIBC = Serum Iron + UIBC. Some labs also measure TIBC directly rather than deriving it, but the two approaches should produce consistent results.
Related Iron Panel Calculators:
- Iron Deficit Calculator : — Estimate total elemental iron replacement needs.
- TSAT Calculator : — Calculate transferrin saturation from serum iron and TIBC.
References:
- Iron-Binding Capacity — StatPearls, National Center for Biotechnology Information (NCBI), National Institutes of Health. https://www.ncbi.nlm.nih.gov/books/NBK559119/
- Iron-Binding Capacity: Reference Range, Interpretation — Medscape/eMedicine. https://emedicine.medscape.com/article/2085726-overview
- Laboratory Procedure Manual: Unsaturated Iron-Binding Capacity (UIBC) — Centers for Disease Control and Prevention (CDC), NHANES. https://wwwn.cdc.gov/nchs/data/nhanes/public/2019/labmethods/FETIB-K-MET-UIBC-508.pdf
Disclaimer: We are developers and health information researchers, not medical professionals. Our calculators are educational tools built from published formulas, not a substitute for clinical assessment or confirmation of a medication dose. Always consult a qualified healthcare provider for medical advice, diagnosis, or treatment.