NAFLD Fibrosis Score Calculator
The NAFLD Fibrosis Score (NFS) uses six routine clinical variables — age, BMI, impaired fasting glucose/diabetes, AST, ALT, platelet count and albumin — to estimate whether advanced hepatic fibrosis (stage F3 or F4) is present or unlikely in patients with NAFLD.
years
kg/m²
Impaired fasting glucose or type 2 diabetes
U/L
U/L
×10⁹/L
g/dL
Indeterminate — further evaluation needed
- 1
AST / ALT ratio
50 ÷ 55 = 0.909 - 2
Positive variable terms
0.037 × 52 + 0.094 × 30 + 1.13 × 0 + 0.99 × 0.909 = 5.644 - 3
Deduction terms
0.013 × 210 + 0.66 × 3.9 = 5.304Higher platelet count and albumin reduce the score, reflecting healthier liver function. - 4
NAFLD Fibrosis Score
−1.675 + 5.644 − 5.304 = -1.335
How does this calculator work?
NFS = −1.675 + 0.037·age + 0.094·BMI + 1.13·IFG + 0.99·(AST/ALT) − 0.013·platelets − 0.66·albumin. Score < −1.455 means advanced fibrosis (F3–F4) is unlikely; > 0.676 means likely; between is indeterminate. Validated by Angulo et al. 2007 for non-invasive NAFLD fibrosis triage.
Formula
How this is calculated
The NAFLD Fibrosis Score was developed and validated by Angulo et al. (Hepatology 2007) as a non-invasive means to identify patients with advanced fibrosis (histological stage F3–F4) without liver biopsy. It combines age and BMI (metabolic risk), the presence of impaired fasting glucose or type 2 diabetes, the AST/ALT ratio (which rises as fibrosis progresses and ALT falls), platelet count (which decreases as portal hypertension develops) and albumin (a marker of synthetic function).
Cutoffs validated in the original cohort: a score below −1.455 makes advanced fibrosis unlikely (negative predictive value ~93%); a score above 0.676 makes it likely (positive predictive value ~90%). Scores in between are indeterminate and warrant further investigation — for example with transient elastography (FibroScan), ELF panel, liver biopsy or specialist referral.
Important limitations: the score was derived from predominantly Caucasian Western cohorts and may perform differently in Asian or paediatric populations. It does not replace clinical judgement; concurrent alcohol use, medications (e.g. methotrexate) and haematological disorders can all affect the variables independently of fibrosis.
Frequently asked questions
The score falls in the indeterminate zone, where the NFS cannot reliably rule in or rule out advanced fibrosis. Most guidelines recommend proceeding to a second-line non-invasive test (e.g. FibroScan) or specialist evaluation rather than biopsy as the next step.
For scores clearly below −1.455 or above 0.676 the NFS can substantially reduce the need for biopsy in clinical practice. Major guidelines (EASL, AASLD) endorse it as a first-line fibrosis triage tool. However, histology remains the reference standard when the diagnosis or fibrosis stage is clinically critical.
Platelet count should be entered in 10⁹ cells per litre (e.g. a count of 210,000/μL = 210 × 10⁹/L → enter 210). Albumin should be entered in grams per decilitre (g/dL) as reported by most clinical laboratories in the US (normal 3.4–5.4 g/dL). European labs may report in g/L — divide by 10 to convert.
Also known as
TG we-Calculate Editorial Team. (2026). NAFLD Fibrosis Score Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/nafld-fibrosis-score-calculator
TG we-Calculate Editorial Team. "NAFLD Fibrosis Score Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/nafld-fibrosis-score-calculator.
TG we-Calculate Editorial Team, "NAFLD Fibrosis Score Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/nafld-fibrosis-score-calculator
@misc{wecalculate_nafld_fibrosis_score_calculator, title = {NAFLD Fibrosis Score Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/nafld-fibrosis-score-calculator}}, year = {2026}, note = {TG we-Calculate} }
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