Transferrin saturation calculator (iron and TIBC)
The percentage of your blood's iron-carrying protein that is loaded with iron right now, worked out from serum iron and TIBC. Type your results in the units on your report and it works out TSAT as you type, in your browser.
AI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-03Iron
Type your results above, or fill in the example, to see TSAT.
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Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.
How it’s worked out
The formula
Transferrin saturation (%) = Serum iron (µg/dL) ÷ TIBC (µg/dL) × 100. Use the same unit for both; µmol/L ÷ µmol/L gives the same percentage. Some labs instead divide iron by a TIBC estimated from measured transferrin.
When the equation works
Outside these limits the calculator says so instead of giving a number.
- Iron can’t be more than the TIBC (above 100%). When it is, the units are usually mixed up.
Fasting before the blood test: recommended. Morning. Because the result is built from serum iron, it varies through the day.
A worked example
Example numbers, not anyone’s real results, run through the same code as the calculator above.
| Iron | 80 µg/dL |
|---|---|
| TIBC | 300 µg/dL |
| TSAT | 27 % |
For an adult, this result is in the usual range.
What TSAT tells you
Transferrin is the protein that carries iron in your blood. Transferrin saturation tells you how full it is. The lab calculates it by dividing serum iron by total iron-binding capacity (TIBC) and multiplying by 100. A low percentage means little iron is available for your body to use. A high percentage means the carrier protein is crowded with iron.
Doctors use transferrin saturation together with ferritin to look at both too little and too much iron. A low value, below about 20%, fits with low iron or with iron being held back by inflammation. A value that stays high, about 45% or more, is the usual first clue to iron overload and often leads to more testing. Serum iron swings during the day, so a single result can mislead.
Read the full page on TSAT, with what a high or low result can mean.
Usual ranges
The ranges the result above is placed on. Your own lab’s printed range comes first if it gives one.
- Adults15–55 %
Sources: Labcorp, ARUP Laboratories, MedlinePlus Medical Encyclopedia (NIH)
Sources
The equation
- Diagnosis and management of hemochromatosis: 2011 practice guideline by the American Association for the Study of Liver Diseases, Hepatology (2011)
- Iron and Total Iron-binding Capacity (TIBC) (test 001321), Labcorp
7 more sources for the ranges and the explanation
- Iron and TIBC sample report (test 001321), Labcorp
- Pediatric Testing Reference Ranges, Labcorp (2022)
- Iron and Iron Binding Capacity (test 0020420), ARUP Laboratories
- Total iron binding capacity, MedlinePlus Medical Encyclopedia (NIH)
- British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults, Gut (2021)
- KDIGO Clinical Practice Guideline for Anemia in Chronic Kidney Disease, Kidney International Supplements (2012)
- EASL Clinical Practice Guidelines on haemochromatosis, Journal of Hepatology (2022)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. The calculator is version 1.0.0 of our code for this equation, tested against published examples. How we build and check these pages.