Key points
- For healthcare professionals assessing adults with known or suspected MASLD.
- Estimates the chance of advanced fibrosis (F3–F4). Accuracy is similar to FIB-4 in people over 35.
- Obesity and diabetes raise the score, so false positives are more common in these groups.
- Runs only in the browser. Nothing typed is stored or sent.
For the evidence, graded recommendations, a case and self-test questions, read Module 1: Assessing liver fibrosis in MASLD.
1Formula and units
NFS = −1.675 + 0.037 × age + 0.094 × BMI + 1.13 × (impaired fasting glucose or diabetes: 1, else 0) + 0.99 × AST/ALT − 0.013 × platelets (10⁹/L) − 0.66 × albumin (g/dL).
The calculator works out BMI from weight and height, and converts albumin from g/L to g/dL (divide by 10) if you choose g/L.
Worked example: age 55, weight 90 kg, height 170 cm (BMI 31.1), diabetes yes, AST 40, ALT 35, platelets 200, albumin 4.2 g/dL → 0.18 → indeterminate.
2How results are labelled
| Score | Label |
|---|---|
| Below −1.455 (below 0.12 if aged 65+) | Low risk |
| From the low cut-off up to 0.676 | Indeterminate |
| Above 0.676 | High risk |
Cut-offs from Angulo 2007; the age-65 cut-off from McPherson 2017.
3Do not rely on NFS alone when
- The patient is under 35 (accuracy is poor).
- BMI is 35 or more, or the patient has diabetes: the score runs high. Confirm with a second-line test.
- Albumin is low for another reason (e.g. kidney or bowel protein loss, malnutrition, acute illness).
- Platelets are low for another reason, or there is acute liver injury.
- Children and pregnancy: not validated.
4Why there is no APRI calculator
APRI was built for hepatitis C. In MASLD it is less accurate than FIB-4 and NFS, and the EASL and AASLD guidance prefer FIB-4 as the first step.
5How we check the calculator
The code is public on GitHub. Before each change we test known values, including the worked example, both age groups and both albumin units.
Related topics
- FIB-4 calculator: method, users and limits
- Non-invasive tests at a glance
- The two-step fibrosis pathway
References
- Angulo P, et al. The NAFLD fibrosis score: a noninvasive system that identifies liver fibrosis in patients with NAFLD. Hepatology 2007;45:846–54. doi:10.1002/hep.21496
- McPherson S, et al. Age as a confounding factor for the accurate non-invasive diagnosis of advanced NAFLD fibrosis. Am J Gastroenterol 2017;112:740–51. doi:10.1038/ajg.2016.453
- Shah AG, et al. Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol 2009;7:1104–12. doi:10.1016/j.cgh.2009.05.033
- EASL–EASD–EASO Clinical Practice Guidelines on the management of MASLD. J Hepatol 2024;81:492–542. doi:10.1016/j.jhep.2024.04.031
- Rinella ME, et al. AASLD Practice Guidance on the clinical assessment and management of NAFLD. Hepatology 2023;77:1797–835. doi:10.1097/HEP.0000000000000323
How to cite this page
Desoky M. NFS calculator: method, users and limits. Metabolic Liver Academy quick reference, version 1.0. Updated 2026-10-03. Available from: https://drmahmouddesoky.github.io/metabolic-liver-academy/ref/nfs-method.html
A summary of published guidelines for healthcare professionals. It does not replace clinical judgement, the full guidelines or local drug labels. Disclaimer.