FIB-4 Index, an Indirect Marker for Liver Fibrosis in Adults (2026 update)

 

Input
 

Type of liver disease	MASLD Non-MASLD
Age		mo yr
Platelets		#/mcL #/microL / nl /mcL /microL /uL 10*3/uL 10*6/uL 10E+9/L 10^3/microL 10e3cells/mcL 10e6 cells/mcL 10e6cells/mcL K/mm3 K/uL Mill/mcl Million/ul Thous/mcL Thousand/uL X10E+09/L X10E+12/L cells/mcL cells/microL cells/uL count/microL m/cmm m/mmm3 thou/mcL x10(12)/L x10(3)/mcL x10(3)/microL x10(6)/L x10(6)/mcL x10(6)/microL x10(9)/L x1000/mm3 x10E3/uL x10E6/uL x10^12/L x10^3/mcL x10^3/microL x10^6/L x10^6/mcL x10^6/microL x10^9/L {cells}/uL
AST		IU/L IntUnit/L U/L Unit/L Units/L mcKat/L
ALT		IU/L IntUnit/L U/L Unit/L Units/L mcKat/L

 

Results
 
Important: Inputs must be complete to perform calculation.

 

FIB-4
Decimal Precision   0 1 2 3

 

FIB-4 interpretation

 

FIB-4 index	Risk
	Cirrhosis less likely
	Indeterminate
	Advanced fibrosis/cirrhosis more likely

 

 

 

 

Notes

• The FIB-4 index ranges for interpretation are based on type of liver disease and patient age.^[2,3,4]
• FIB-4 accuracy is low in patients under 35 years of age.^[2,4]
• The normal Platelet count range is 150,000 to 400,000/microL [150 to 400 X 10⁹/L].
• ALT: alanine aminotransferase; AST: aspartate aminotransferase; FIB-4: Fibrosis-4; MASLD: metabolic dysfunction-associated steatotic liver disease.

 
Equations used
 

FIB-4 = Age * AST / (0.001 * Platelets * sqr(ALT))

 

 

References

1. Vallet-Pichard A, Mallet V, Nalpas B, et al. FIB-4: an inexpensive and accurate marker of fibrosis in HCV infection. Comparison with liver biopsy and fibrotest. Hepatology. 2007; 46:32. PubMed ID: 17567829
2. McPherson S, Hardy T, Dufour JF, et al. Age as a Confounding Factor for the Accurate Non-Invasive Diagnosis of Advanced NAFLD Fibrosis. Am J Gastroenterol. 2017; 112:740. PubMed ID: 27725647
3. Sterling RK, Patel K, Duarte-Rojo A, et al. AASLD Practice Guideline on blood-based noninvasive liver disease assessment of hepatic fibrosis and steatosis. Hepatology. 2025; 81:321. PubMed ID: 38489523
4. Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023; 77:1797. PubMed ID: 36727674