The Fibrosis-4 (FIB-4) index estimates the likelihood of advanced liver fibrosis from four routine values: your age and three blood-test results. Enter them below for the score and its risk category.
This tool is for general information and education only. It is not a diagnosis and does not replace medical advice. Discuss any liver-health concern and your results with a doctor.
Above 2.67 — a higher-risk result; specialist assessment is usually advised.
Score2.92
CategoryHigh risk
Standard cut-offs (ages 36–64): below 1.3 makes advanced fibrosis unlikely; 1.3–2.67 is indeterminate; above 2.67 suggests advanced fibrosis. In adults 65+ a lower cut-off of 2.0 is used for the low-risk threshold.
FIB-4 is a widely used, non-invasive score that helps decide who needs further liver investigation. It combines age with two liver enzymes (AST and ALT) and the platelet count, all of which are usually available from a standard blood panel, so it can be worked out without a special test.
The FIB-4 formula
FIB-4 = (Age × AST) ÷ (Platelets × √ALT) Age in years, AST and ALT in U/L, platelets in ×10⁹/L.
Worked example
A 60-year-old with AST 40, ALT 30 and platelets 150: FIB-4 = (60 × 40) ÷ (150 × √30) = 2,400 ÷ (150 × 5.477) = 2,400 ÷ 821.6 = 2.92. That is above 2.67, so specialist assessment would usually be advised.
How to read the score
For most adults aged 36–64, a FIB-4 under 1.3 makes advanced fibrosis unlikely and often needs no further testing; 1.3 to 2.67 is an indeterminate zone that may prompt a further test such as elastography; and above 2.67 points to a higher chance of advanced fibrosis and referral. In people aged 65 and over the lower cut-off rises to 2.0 because the score naturally increases with age.
Frequently asked questions
What does a high FIB-4 mean?
A score above the upper cut-off suggests a higher chance of advanced liver scarring and usually leads to a referral for further tests. It is not a diagnosis on its own.
Where do I get AST, ALT and platelets?
All three come from routine blood tests — a liver function test for AST and ALT, and a full blood count for platelets. Use the values from the same sample.
Is FIB-4 accurate on its own?
It is a screening aid, not a diagnosis. Results in the indeterminate range, or any concern, are followed up with more specific tests like elastography.
Does age change the result?
Yes — age is in the formula and the score tends to rise with age, which is why a higher low-risk cut-off (2.0) is used for people 65 and over.
For general information only — not medical advice, diagnosis or treatment. Always consult a qualified clinician about your health and test results.
Written by the CalcPine team · Reviewed for accuracy · Last updated 23 July 2026 · Method: FIB-4 = (age × AST) / (platelets × √ALT); standard cut-offs 1.3 and 2.67.
