FIB-4 Index Calculator
Screen for advanced liver fibrosis from age, AST, ALT, and platelet count.
Low probability of advanced liver fibrosis
A screening estimate, not a diagnosis. FIB-4 helps identify who is unlikely to have advanced fibrosis and who may need further testing (such as elastography or biopsy) — it doesn't diagnose liver disease on its own, and can be less reliable in patients over 65 or with certain other conditions. Discuss results with a healthcare provider.
How FIB-4 is calculated
Interpreting the score
| FIB-4 | Interpretation |
|---|---|
| < 1.45 | Low probability of advanced fibrosis |
| 1.45–3.25 | Indeterminate |
| > 3.25 | High probability of advanced fibrosis |
Source: Sterling RK, et al. Hepatology. 2006;43(6):1317-25.
Common questions
FIB-4 is a noninvasive score that combines age, AST, ALT, and platelet count to estimate the likelihood of advanced liver fibrosis. It was originally developed and validated in patients with HIV/hepatitis C coinfection and is now widely used more broadly, including in fatty liver disease (NAFLD/MASLD) screening.