MELD Score Calculator
Calculate MELD, MELD-Na, and MELD 3.0 scores for liver disease severity and 3-month mortality-oriented reference context.
NAFLD Fibrosis Score Calculator
Calculate the NAFLD Fibrosis Score (NFS) to assess liver fibrosis severity in fatty liver disease. Also computes FIB-4 and APRI for comparison.
⚠️ Medical Disclaimer: The NFS is a screening tool for advanced fibrosis in NAFLD/MASLD. Liver biopsy remains the gold standard. Clinical decisions should involve hepatology consultation. Scores in the indeterminate range require further evaluation.
years
kg/m²
U/L
U/L
×10⁹/L
g/dL
Low (<-1.455)IndeterminateHigh (>0.676)
NAFLD Fibrosis Score
0.428
Indeterminate
Score falls in the indeterminate range — consider further evaluation
NFS
0.43
Indeterminate
FIB-4
2.01
Indeterminate
APRI
0.76
Normal
NFS Score⧉
0.428
Indeterminate
Fibrosis Stage⧉
Indeterminate
Score falls in the indeterminate range — consider further evaluation
FIB-4 Index⧉
2.01
Indeterminate
AST/ALT Ratio⧉
0.79
Ratio <1 typical for early NAFLD
APRI Score⧉
0.76
<1.0 low risk
Next Step⧉
Liver biopsy or elastography recommended
Based on NFS classification
| NFS Range | Fibrosis | NPV/PPV | Action |
|---|---|---|---|
| < −1.455 | F0-F2 | NPV 93% | Reassess in 3-5 years; lifestyle modification |
| −1.455 to 0.676 | Indeterminate | — | FibroScan or liver biopsy needed |
| > 0.676 | F3-F4 | PPV 82% | Hepatology referral, monitor for decompensation |
| Variable | Value | Impact on NFS |
|---|---|---|
| Age | 55 years | Older age increases score |
| BMI | 32 kg/m² | Higher BMI increases score |
| Diabetes | Type 2 | DM/IFG adds 1.13 to score |
| AST/ALT Ratio | 0.79 | Higher ratio → more fibrosis |
| Platelets | 180 ×10⁹/L | Lower platelets → more fibrosis (portal HTN) |
| Albumin | 3.8 g/dL | Lower albumin → worse synthetic function |
Planning notes, formulas, and examples
About the NAFLD Fibrosis Score Calculator
The NAFLD Fibrosis Score (NFS) is a validated, non-invasive tool for identifying advanced liver fibrosis (F3-F4) in patients with non-alcoholic fatty liver disease (NAFLD), now renamed metabolic dysfunction-associated steatotic liver disease (MASLD). Using six readily available clinical and laboratory variables — age, BMI, diabetes status, AST/ALT ratio, platelet count, and albumin — it stratifies patients into low, indeterminate, and high probability of advanced fibrosis.
NAFLD/MASLD affects approximately 25-30% of the global adult population and is the leading cause of chronic liver disease in developed countries. While most patients have simple steatosis with benign prognosis, 10-15% progress to non-alcoholic steatohepatitis (NASH) and potentially cirrhosis. The critical clinical question is identifying the subset with advanced fibrosis, as they face significantly increased liver-related and overall mortality.
This calculator also provides FIB-4 and APRI scores for comparison, as current guidelines recommend using multiple non-invasive tests in a stepwise algorithm before proceeding to liver biopsy.
When This Page Helps
Liver biopsy, while the gold standard, is invasive, costly, subject to sampling error, and carries procedural risk (pain in 30%, significant complications in 0.5%). Non-invasive scores like NFS can reliably rule out advanced fibrosis (NPV >93% at the low cutoff), avoiding unnecessary biopsies in the majority of NAFLD patients.
Current AASLD and EASL guidelines recommend NFS or FIB-4 as first-line screening tools, with liver elastography (FibroScan) as a second-line test for patients in the indeterminate range.
How to Use the Inputs
- Enter patient demographics: age and BMI.
- Select diabetes status (none, IFG/IGT, or type 2 diabetes).
- Enter liver function tests: AST and ALT.
- Enter platelet count and albumin.
- Review NFS classification and comparison with FIB-4 and APRI.
- Use the recommended next steps based on the NFS category.
Formula used
NFS = −1.675 + 0.037 × age + 0.094 × BMI + 1.13 × IFG/Diabetes(yes=1) + 0.99 × AST/ALT ratio − 0.013 × platelets − 0.66 × albumin
Low cutoff: < −1.455 → F0-F2 (NPV 93%)
High cutoff: > 0.676 → F3-F4 (PPV 82%)
FIB-4 = (Age × AST) / (Platelets × √ALT)
APRI = ((AST / ULN) × 100) / PlateletsExample Calculation
Result: NFS 0.45 — Indeterminate
The NFS of 0.45 falls in the indeterminate zone (-1.455 to 0.676). This means advanced fibrosis cannot be confidently ruled in or out by blood tests alone. The recommended next step is liver elastography (FibroScan); if elastography is also indeterminate, liver biopsy may be needed.
Tips & Best Practices
- Use NFS as a first-line screening tool — reserve biopsy for indeterminate cases after elastography.
- In patients >65, consider adjusted cutoffs to reduce false positives from age-related score inflation.
- An AST/ALT ratio >1 in NAFLD should raise concern for advanced fibrosis or cirrhosis.
- Thrombocytopenia (<150 × 10⁹/L) in NAFLD is an independent marker of portal hypertension.
- Combine NFS with FIB-4 for higher confidence — concordant results are more reliable than either alone.
- Weight loss of ≥10% can improve fibrosis stage and NFS score over 12-24 months.
NAFLD/MASLD Fibrosis Staging
Histological fibrosis is staged F0-F4: F0 (no fibrosis), F1 (perisinusoidal/portal), F2 (perisinusoidal + portal), F3 (bridging fibrosis), F4 (cirrhosis). The clinical significance is primarily in distinguishing F0-F2 (low risk) from F3-F4 (significant liver-related mortality risk). Patients with F3-F4 fibrosis have a 10-year liver-related mortality of 10-25%.
Treatment Implications by Fibrosis Stage
All NAFLD patients should receive lifestyle counseling. For F0-F2: weight loss (7-10% body weight), exercise, and cardiometabolic risk factor management. For F3-F4: aggressive weight management, consideration of GLP-1 receptor agonists or resmetirom (recently FDA-approved for NASH with F2-F3 fibrosis), hepatocellular carcinoma surveillance, and variceal screening.
The Sequential Algorithm
The recommended approach: Step 1 — NFS or FIB-4 (rules out advanced fibrosis in ~60% of patients). Step 2 — FibroScan or Enhanced Liver Fibrosis (ELF) test for indeterminate cases. Step 3 — Liver biopsy if non-invasive tests remain discordant or indeterminate. This algorithm avoids biopsy in approximately 70-80% of patients while maintaining diagnostic accuracy.
Sources & Methodology
Last updated:
Methodology
This calculator applies the original six-variable NAFLD Fibrosis Score equation using age, BMI, impaired fasting glucose or diabetes as a binary term, AST/ALT ratio, platelets in 10^9/L, and albumin in g/dL, then interprets the result with the original low and high cut points of -1.455 and 0.676. The page also shows FIB-4 and APRI as comparison tools, but those should be treated as parallel noninvasive fibrosis screens rather than interchangeable formulas.
The score is intended for adult NAFLD or MASLD fibrosis triage, not as a stand-alone diagnosis of cirrhosis or biopsy replacement in every setting. When APRI is displayed, this page assumes an AST upper limit of normal of 40 U/L, so labs using materially different reference ranges should interpret the APRI number cautiously.
Sources
Frequently Asked Questions
In 2023, a multi-society consensus renamed NAFLD to MASLD (metabolic dysfunction-associated steatotic liver disease). MASLD requires hepatic steatosis PLUS at least one cardiometabolic risk factor (BMI ≥25, diabetes, hypertension, dyslipidemia, waist circumference criteria). The NFS remains valid under both nomenclatures.
NFS and FIB-4 are blood-based scores ideal for initial screening (high NPV). FibroScan (transient elastography) provides a direct measurement of liver stiffness (in kPa) with better accuracy for intermediate-risk patients. Current guidelines recommend a sequential approach: NFS/FIB-4 first, then FibroScan for indeterminate cases.
NFS was specifically developed and validated for NAFLD/MASLD. It has not been validated in hepatitis B/C, alcoholic liver disease, autoimmune hepatitis, or other etiologies. FIB-4 has broader validation across multiple liver disease etiologies.
Approximately 25-35% of NAFLD patients fall in the indeterminate zone. These patients require additional testing — typically liver elastography. If FibroScan liver stiffness is <8 kPa, advanced fibrosis is unlikely; if >12 kPa, it is probable. Values 8-12 kPa may warrant biopsy.
Yes. NFS has lower specificity in patients over 65 years because age itself increases the score. Some authors suggest using an adjusted high cutoff of >0.12 instead of >0.676 for patients >65 years to reduce false positives.
For patients with low NFS: repeat every 3-5 years unless clinical status changes. For indeterminate or high NFS patients under treatment: repeat every 1-2 years to assess treatment response. Improvement in NFS (moving from high to indeterminate or low) correlates with histological regression.
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