What is my FIB-4 score?
Enter your age, AST, ALT, and platelet count from routine blood tests to calculate the FIB-4 index for liver scarring (fibrosis). For information only. This is not medical advice or a diagnosis. Do not use it to make treatment decisions without a clinician. No licensed clinician has reviewed this page.
- FIB-4
- 1.77
The FIB-4 index is 1.77. Indeterminate: further testing is often needed.
- What the cut-offs say
- Indeterminate: further testing is often needed
- Cut-offs used
- under 1.30 low, over 2.67 high
FIB-4: 1.77. The FIB-4 index is 1.77. Indeterminate: further testing is often needed.
FIB-4 on a 0 to 5 scale
This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use
How to calculate
Calculates the FIB-4 liver fibrosis index from age, AST, ALT, and platelet count (Sterling 2006) and reads it with the published cut-offs for fatty liver disease (MASLD) or for hepatitis C and HIV.
Example with the default inputs (Liver condition Fatty liver (MASLD), Age 55, AST (U/L) 40, ALT (U/L) 35, Platelets (×10⁹/L) 210): The FIB-4 index is 1.77. Indeterminate: further testing is often needed.
Method: FIB-4 = (age × AST) ÷ (platelets × √ALT), with AST and ALT in U/L and platelets in 10⁹/L.
- The index is rounded to 2 decimals and read from the rounded value.
- MASLD: under 1.30 low (under 2.00 at age 65 or older), over 2.67 high (Shah 2009, McPherson 2017, AASLD 2023). Hepatitis C or HIV: under 1.45 low, over 3.25 high (Sterling 2006).
- FIB-4 is less accurate under age 35 and in acute hepatitis.
Worked examples
Each example is checked against the calculator on every build.
- Liver condition Fatty liver (MASLD), Age 55, AST (U/L) 40, ALT (U/L) 35, Platelets (×10⁹/L) 210 gives FIB-4 1.77, What the cut-offs say Indeterminate: further testing is often needed.Source: Sterling 2006: FIB-4 = (55 × 40) ÷ (210 × √35) = 1.7709, shown as 1.77; MASLD cut-offs 1.30 and 2.67 (Shah 2009)
- Liver condition Fatty liver (MASLD), Age 45, AST (U/L) 25, ALT (U/L) 30, Platelets (×10⁹/L) 250 gives FIB-4 0.82, What the cut-offs say Low: advanced fibrosis is unlikely.
- Liver condition Hepatitis C or HIV, Age 62, AST (U/L) 90, ALT (U/L) 60, Platelets (×10⁹/L) 110 gives FIB-4 6.55, What the cut-offs say High: advanced fibrosis is likely.Source: (62 × 90) ÷ (110 × √60) = 6.5490, over 3.25 (Sterling 2006)
- Liver condition Fatty liver (MASLD), Age 70, AST (U/L) 30, ALT (U/L) 25, Platelets (×10⁹/L) 200 gives FIB-4 2.1, What the cut-offs say Indeterminate: further testing is often needed, Cut-offs used under 2.00 low, over 2.67 high.
Medical disclaimer
This calculator is for information and education only. It is not medical advice, and its result is not a diagnosis. Do not use it to start, stop, or change a treatment without a clinician who knows your health history. No licensed clinician has reviewed this page. This site's editors checked the formulas and worked examples against published sources. If you think you have a medical emergency, call your local emergency number.
When this does not apply. FIB-4 is for adults with a chronic liver disease: fatty liver disease (Shah 2009, McPherson 2017) or hepatitis C and HIV (Sterling 2006). It performs poorly at 35 or younger and less well at 65 or older (McPherson 2017). It does not apply to acute hepatitis.
How the index is worked out
FIB-4 = (age × AST) ÷ (platelets × √ALT)
- Age in years; AST and ALT in U/L; platelets in 10⁹/L (the same number as 10³/µL).
- The index is rounded to 2 decimal places (halves round up, read from the decimal value: a result within 1e-9 (relative) of a half counts as the half, so 2.005 rounds to 2.01), and the reading uses the rounded value.
Cut-offs
| Condition | Low: advanced fibrosis unlikely | Indeterminate | High: advanced fibrosis likely |
|---|---|---|---|
| Fatty liver (MASLD), under 65 | under 1.30 | 1.30 to 2.67 | over 2.67 |
| Fatty liver (MASLD), 65 or older | under 2.00 | 2.00 to 2.67 | over 2.67 |
| Hepatitis C or HIV | under 1.45 | 1.45 to 3.25 | over 3.25 |
MASLD cut-offs: Shah 2009, with the age 65 cut-off from McPherson 2017, as used in the AASLD 2023 guidance. Hepatitis C and HIV: Sterling 2006. A value equal to a cut-off is indeterminate.
Inputs the calculator accepts
Age 18 to 110, AST and ALT 1 to 10,000 U/L, platelets 1 to 2,000 ×10⁹/L.
Worked examples by hand
The default (MASLD). Age 55, AST 40, ALT 35, platelets 210: √35 = 5.9161. FIB-4 = 2,200 ÷ (210 × 5.9161) = 2,200 ÷ 1,242.38 = 1.77, between 1.30 and 2.67, so indeterminate.
Low (MASLD). Age 45, AST 25, ALT 30, platelets 250: 1,125 ÷ (250 × 5.4772) = 0.82, under 1.30.
High (hepatitis C). Age 62, AST 90, ALT 60, platelets 110: 5,580 ÷ (110 × 7.7460) = 6.55, over 3.25.
Age 65 or older (MASLD). Age 70, AST 30, ALT 25, platelets 200: 2,100 ÷ (200 × 5) = 2.10. The low cut-off at this age is 2.00, so the reading is indeterminate.
Other questions people ask
What is the FIB-4 score?
FIB-4 (fibrosis-4) is an index from four routine values: age, the liver enzymes AST and ALT, and the platelet count. Sterling and others built it in 2006 to estimate how much scarring (fibrosis) there is in the liver without a biopsy. It is best at ruling out advanced fibrosis.
What is a normal FIB-4?
For fatty liver disease (MASLD, formerly NAFLD), a FIB-4 under 1.30 means advanced fibrosis is unlikely, and over 2.67 means it is likely (Shah 2009). From age 65, the low cut-off is 2.0, because FIB-4 rises with age (McPherson 2017). For hepatitis C or HIV, Sterling used under 1.45 and over 3.25.
What happens with an indeterminate FIB-4?
A result between the two cut-offs cannot rule fibrosis in or out. The AASLD 2023 guidance on MASLD suggests a second test, such as liver stiffness by elastography or the ELF blood test. Your clinician decides what fits.
Why does age matter?
Age is part of the formula, so the index rises with age even when the liver is the same. That makes the low cut-off less reliable in people 65 or older, and the index is not well studied under age 35.
What units does FIB-4 use?
AST and ALT in units per liter (U/L), and platelets in 10⁹ per liter, which is the same number as thousands per microliter. A platelet count of 210,000/µL is 210.