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FIB-4 Liver Fibrosis Index Calculator

FIB-4 = (Age · AST) / (Platelet · √ALT).

Compute the FIB-4 index — a non-invasive estimate of advanced liver fibrosis combining age, AST, ALT and platelet count: FIB-4 = (age × AST) / (platelets × √ALT). Values < 1.45 rule out, > 3.25 rule in advanced fibrosis.

Priya Venkatesan By Priya Venkatesan
Published Last reviewed 1 min read

Inputs

yrs
IU/L
IU/L
×10⁹/L

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

FIB-4 = (Age · AST) / (Platelet · √ALT)

In depth

Compute the FIB-4 index — a non-invasive estimate of advanced liver fibrosis combining age, AST, ALT and platelet count: FIB-4 = (age × AST) / (platelets × √ALT). Values < 1.45 rule out, > 3.25 rule in advanced fibrosis.