FIB-4 (Fibrosis-4 Index) Non-Invasive Liver Fibrosis Score Calculator

Calculate FIB-4 = (Age × AST) / (Platelets_10⁹/L × √ALT) and APRI score.

FIB-4 Liver Fibrosis Index
1.84 index
APRI Score (AST-to-Platelet Index) 0.65 index
De Ritis Ratio (AST ÷ ALT) 0.89 ratio
Platelet Count 185 ×10⁹/L
Inputs
⚡ Scenarios:
years
Patient age in years.
U/L
Aspartate Aminotransferase (AST) in U/L.
U/L
Alanine Aminotransferase (ALT) in U/L.
×10⁹/L
Platelet count in ×10⁹/L (or ×10³/μL; e.g., 185 for 185,000/μL).
Results & Graph
FIB-4 Liver Fibrosis Index
1.84 index
APRI Score (AST-to-Platelet Index)
0.65 index
De Ritis Ratio (AST ÷ ALT)
0.89 ratio
Platelet Count
185 ×10⁹/L

FIB-4 Liver Fibrosis Index

Graph 1 • FIB-4 Liver Fibrosis Index • Domain Architecture & Live Telemetry Maps Patient Age Years, Ast Level U L, Alt Level U L through FIB-4 Liver Fibrosis Index Formula.
FIB-4 Liver Fibrosis Index • Clinical & Physiological Reference Scale Low / Baseline Target / Reference Elevated / Watch High / Action FIB-4 Liver Fibrosis Index: 1.84 index APRI Score (AST-to-Platele 0.65 index De Ritis Ratio (AST ÷ ALT) 0.89 ratio Platelet Count 185 ×10⁹/L
Graph 2 • FIB-4 Liver Fibrosis Index Across Patient Age Years Sweep (40% → 160%) Evaluates FIB-4 = (Age_years × AST_U_L) / (Platelets_10⁹_L × √(ALT_U_L)) across 7 operating points (current input highlighted).
0 index 1.62 index 3.23 index 0.730 20.80years 1.10 31.20years 1.47 41.60years 1.84 52years 2.20 62.40years 2.57 72.80years 2.94 83.20years
Graph 3 • Joint Sensitivity: Patient Age Years × Ast Level U L Compares FIB-4 Liver Fibrosis Index when Ast Level U L is shifted +25% (solid) vs. −25% (dashed).
0 index 1.64 index 3.28 index --- Ast Level U L @ 75% 1.61 -30% 1.95 -15% 2.30 +0% 2.64 +15% 2.98 +30%
Summary: FIB-4 is 1.84 (Indeterminate (1.30–2.67)), APRI score is 0.65, and AST/ALT (De Ritis) ratio is 0.89.
Summary: FIB-4 is 1.84 (Indeterminate (1.30–2.67)), APRI score is 0.65, and AST/ALT (De Ritis) ratio is 0.89.
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Formula & Mathematical Methodology: FIB-4 Liver Fibrosis Index Formula

FIB-4 = Ageyears × ASTULPlatelets10⁹L × ALTUL
FIB-4 = (Age_years × AST_U_L) / (Platelets_10⁹_L × √(ALT_U_L))
  • patientAgeYears: Patient Age Years (years)
  • astLevelUL: Ast Level U L (U/L)
  • altLevelUL: Alt Level U L (U/L)
  • plateletCount10e9L: Platelet Count10e9 L (×10⁹/L)

Rounding: Clinical scores round to statutory integer or decimal precision; physiological metrics round to 2 decimal places.

Worked Example: Clinical / Physiology Scenario: FIB-4 Liver Fibrosis Index

Calculate FIB-4 = (Age × AST) / (Platelets_10⁹/L × √ALT) and APRI score.

  1. Enter lab values, anthropometric measurements, or performance test metrics.
  2. Evaluate the reference equation: FIB-4 = (Age_years × AST_U_L) / (Platelets_10⁹_L × √(ALT_U_L)).
  3. Inspect the primary classification, supporting indices, and 3 SVG charts.
Result: Computes FIB-4 Liver Fibrosis Index via FIB-4 = (Age_years × AST_U_L) / (Platelets_10⁹_L × √(ALT_U_L)).

Frequently Asked Questions

How does the FIB-4 (Fibrosis-4 Index) Non-Invasive Liver Fibrosis Score Calculator compute its result?

It evaluates FIB-4 = (Age_years × AST_U_L) / (Platelets_10⁹_L × √(ALT_U_L)) directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a target lab value or pace?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Are my health and biometric inputs kept private?

Yes. All calculations run 100% locally on your device with zero external transmission.

Health & Fitness · Hepatology, GI & Cardiology Scores

FIB-4 (Fibrosis-4 Index) Non-Invasive Liver Fibrosis Score Calculator: inputs, method, and how to read the result

Calculate FIB-4 = (Age × AST) / (Platelets_10⁹/L × √ALT) and APRI score.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Patient Age Years: Patient age in years.
  • Ast Level U L: Aspartate Aminotransferase (AST) in U/L.
  • Alt Level U L: Alanine Aminotransferase (ALT) in U/L.
  • Platelet Count10e9 L: Platelet count in ×10⁹/L (or ×10³/μL; e.g., 185 for 185,000/μL).

What the calculation includes

With the default values shown, FIB-4 Liver Fibrosis Index is 1.84 index. The calculation follows FIB-4 Liver Fibrosis Index Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Patient Age Years from 52 years to 57 years changes FIB-4 Liver Fibrosis Index from 1.84 index to 2.01 index. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses peer-reviewed clinical and sports physiology formulas.
  • For educational and informational reference only; clinical scores do not replace physician judgment or laboratory reference ranges.

Scope: Global Clinical & Sports Science Consensus Check the assumptions and limitations against your situation before relying on the estimate.

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