FIB-4 Calculator: What Your Liver Fibrosis Score Means
FIB-4 is a score built from your age, AST, ALT and platelet count. It estimates the chance of advanced liver scarring (fibrosis). Below 1.30 (below 2.00 if you’re 65 or over), advanced fibrosis is unlikely. From 1.30 (or 2.00) up to 2.67, the result is indeterminate and usually leads to a second test: FibroScan in the US, often an ELF blood test in the UK. Above 2.67, advanced fibrosis is more likely and most pathways involve a liver specialist.
Units: AST and ALT are in U/L (also written IU/L) in both countries. Platelets ×10⁹/L (UK) and ×10³/µL (US) are the same number.
FIB-4 calculator
Enter your age and three results from the same blood test. Everything is worked out on your device, and nothing is saved or sent anywhere.
FIB-4 score chart
These bands follow the American Association for the Study of Liver Diseases (AASLD, 2023) and the European EASL-EASD-EASO guideline (2024). From age 65, the lower cut-off moves up to 2.00. Many UK pathways use 3.25 as the upper cut-off.
Sources: AASLD 2023; EASL-EASD-EASO 2024; McPherson 2017; BSG 2018 (Newsome); Sterling 2006.
| Under 65 | 65 and over | Band | What usually happens next |
|---|---|---|---|
| Below 1.30 | Below 2.00 | Low risk | Usual doctor; repeat in 1 to 3 years |
| 1.30 to 2.67 | 2.00 to 2.67 | Indeterminate | Second test: FibroScan (US) or ELF (UK) |
| Above 2.67 | Above 2.67 | High risk | Elastography and a liver specialist |
What FIB-4 actually tells you
Fibrosis is scar tissue that builds up when the liver is injured again and again over years. The most common driver is metabolic dysfunction-associated steatotic liver disease (MASLD), the 2023 name for non-alcoholic fatty liver disease (NAFLD). EASL defines it as extra liver fat plus at least one cardiometabolic risk factor, such as excess waist size, raised blood sugar, high blood pressure or abnormal blood fats. The British Liver Trust estimates it affects up to 1 in 5 people in the UK.
Fat alone can be fully reversed. Scarring runs from stage 0 to stage 4 (cirrhosis), and FIB-4 aims to catch stages 3 and 4, called advanced fibrosis. Like a detective reading footprints, it never sees the scar tissue, only indirect traces in routine blood tests. Platelets, for example, can fall as scarring raises pressure in the liver’s blood supply (EASL 2021).
How FIB-4 is calculated
Units age in years, AST and ALT in U/L, platelets in ×10⁹/L (= ×10³/µL)
Example: age 52, AST 30, ALT 25, platelets 250:
= 1560 ÷ 1250 = 1.25 (low risk)
The platelet number is the same on US and UK reports, because 10³ per microliter equals 10⁹ per liter.
Where the numbers come from. Sterling and colleagues built FIB-4 in 2006 from 832 people with HIV and hepatitis C, with cut-offs of 1.45 and 3.25. In 2009, Shah and colleagues tested it in 541 adults with fatty liver disease. A score of 1.30 or less had a 90% negative predictive value (9 in 10 people at or below it did not have advanced fibrosis). A score of 2.67 or more had an 80% positive predictive value. AASLD and EASL use these cut-offs today. McPherson and colleagues (2017) found too many false alarms from age 65 and proposed 2.00 as the lower cut-off.
Rounding: the score is rounded to 2 decimals, halves up, and the rounded score is banded. As in the AASLD ranges, exactly 1.30 and exactly 2.67 count as indeterminate. The 2.00 cut-off applies from age 65, as in McPherson’s study. BSG and EASL word it as “over 65”.
What your FIB-4 score means
Each band is a case file: clues, usual suspects, the next lead and what guidelines say. A score is a probability, never a diagnosis.
Below 1.30 (below 2.00 if 65 or over)
- Advanced fibrosis is unlikely
- A low score today can rise later
- Early MASLD, or no liver disease
- Risk factors still worth tackling: insulin resistance, blood sugar and blood fats
Repeat FIB-4 every 1 to 3 years (EASL), or every 1 to 2 years with prediabetes, type 2 diabetes or two or more metabolic risk factors (AASLD).
AASLD 2023: patients in low-risk categories can be managed in primary care.
Ask: When should we repeat this? Which of my risk factors matters most for my liver?
1.30 to 2.67 (2.00 to 2.67 if 65 or over)
- FIB-4 can’t rule advanced fibrosis in or out here
- Older age alone pushes scores up
- MASLD with some scarring
- A low platelet count or high AST from another cause
A second test. In the US, usually FibroScan: below 8 kPa rules out advanced fibrosis. In the UK, often an ELF blood test, with referral at 9.8 or above where pathways follow the 2024 change.
AASLD 2023: if FIB-4 is 1.3 or more, FibroScan (VCTE), MR elastography or ELF may be used to exclude advanced fibrosis. EASL 2024 uses the same 1.3 trigger.
Ask: Which second test do I need? Could anything else explain my AST or platelets?
Above 2.67
- Advanced fibrosis is more likely: 8 in 10 people scoring 2.67 or more had it in Shah’s study
- It can still be a false alarm
- MASLD with advanced scarring
- Alcohol-related liver disease
- Long-standing hepatitis B or C
- A non-liver cause of high AST or low platelets
Elastography and a liver team. Albumin and bilirubin help show how well the liver is working.
AGA 2021: care led by a hepatologist. BSG 2018 (UK): above 3.25, consider referral whatever the second test shows.
Ask: Do I need a FibroScan or a specialist referral? What could be damaging my liver?
What can throw off a FIB-4 score
- Age 35 or younger. FIB-4 performed poorly at this age (McPherson 2017), so a low score is less reassuring.
- Age 65 or over. With the 1.30 cut-off, specificity fell to 35%, meaning many false alarms. Using 2.00 raised it to 70% (McPherson 2017).
- AST from outside the liver. AST is also found in heart and skeletal muscle. Muscle injury, strenuous exercise and hemolysis (red cells breaking down) can raise it (ACG 2017), and that raises FIB-4.
- Low platelets for another reason. The formula can’t tell why platelets are low. See our full blood count guide.
- A sudden liver injury. FIB-4 was built in long-standing liver disease. During an acute flare, ask whether to repeat it once levels settle.
- Normal enzymes. AASLD notes liver enzymes are often normal in advanced liver disease. A higher ALT actually lowers the score.
- Type 2 diabetes. AASLD says these tests may perform less well in people with diabetes.
US vs UK: what usually happens after FIB-4
Both countries start with FIB-4. US guidance leans on FibroScan, a scan that measures liver stiffness. Many UK pathways use the ELF blood test, which measures markers of scar tissue directly. AASLD accepts either.
| Step | US (AASLD 2023, AGA 2021) | UK (NICE, BSG) |
|---|---|---|
| FIB-4 cut-offs | 1.30 and 2.67 | Often 1.30 and 3.25 (BSG 2018), with 2.00 as the lower cut-off over 65. Local pathways vary. |
| Second test | FibroScan (VCTE) first, or MR elastography or ELF | Usually ELF. Some areas add FibroScan. |
| Second-test cut-offs | FibroScan below 8 kPa rules out advanced fibrosis; above 12 kPa makes it likely | ELF 9.8 or above: refer (Health Technology Wales 2024, endorsed by the BSG). NICE NG49 (2016) still says 10.51. Some areas use 9.5 and 11.3. |
| Repeat testing | FIB-4 every 1 to 2 years with diabetes, prediabetes or two or more metabolic risk factors | NICE: ELF every 3 years for adults below the cut-off |
FibroScan needs at least 3 hours of fasting (EASL 2021). ELF needs only a blood sample, so a GP can order it without a scanner.
Special groups
- Under 35 and over 65: see the age cautions above.
- Type 2 diabetes: AASLD and EASL both advise checking for advanced fibrosis. Tracking insulin resistance? Try our HOMA-IR calculator.
- Children: FIB-4 was developed in adults. NICE refers children with suspected NAFLD to a pediatric liver specialist.
Reading FIB-4 on your lab report or app
Most reports print AST, ALT and platelets separately. AST and ALT appear in liver function tests (LFTs), sometimes as SGOT and SGPT on older US reports. Platelets (PLT) sit in the CBC (US) or full blood count, FBC (UK). US reports print ×10³/µL or K/µL and UK reports ×10⁹/L, with the same number. If your report shows 250,000 per µL, enter 250.
Use results from the same blood draw if you can. If your patient portal or the NHS App already shows a FIB-4 value, check which cut-offs your service uses.
When to get help urgently
- See a doctor straight away if you have liver disease and you vomit blood, pass very dark or black tarry stools, have confusion or drowsiness, a high fever with shivers, or shortness of breath (British Liver Trust). In an emergency, call 911 (US) or 999 (UK).
- New yellowing of your skin or the whites of your eyes, or a swelling tummy: contact your doctor promptly.
FIB-4 questions people ask
What is a normal FIB-4 score?
There’s no normal range. Below 1.30 (below 2.00 at 65 or over), advanced fibrosis is unlikely. Above 2.67, it’s more likely.
What does a FIB-4 of 1.3 to 2.67 mean?
It’s indeterminate: the score can’t rule advanced fibrosis in or out, so guidelines suggest FibroScan or an ELF blood test next.
How accurate is FIB-4?
It’s best at ruling out. In fatty liver disease, 9 in 10 people scoring 1.30 or less didn’t have advanced fibrosis, and 8 in 10 scoring 2.67 or more did (Shah 2009).
ELF test vs FibroScan: which is better?
AASLD accepts either as the second test. FibroScan measures liver stiffness with a scan; ELF is a blood test. The UK leans on ELF and US practice on FibroScan.
Can a high FIB-4 be wrong?
Yes. Age over 65, muscle injury, hard exercise, hemolysis or low platelets from another cause can push it up.
Can my FIB-4 score go down?
Yes, as your results change. The British Liver Trust says healthy living can slow or even reverse liver damage, especially at earlier stages.
How we wrote this page
Written and medically reviewed by Dr. Mustafa Sakr, MBBCh. Last reviewed: October 2026. The numbers come from the original FIB-4 studies, AASLD, AGA, EASL, NICE, the BSG and Health Technology Wales, listed below. We update this page when guidance changes.
How the calculator works: it applies (age × AST) ÷ (platelets × √ALT), rounds to 2 decimals, and compares the result with 1.30 (2.00 from age 65) and 2.67. It flags results that are harder to read, such as age 35 or under or very high enzymes. It runs on your device, stores nothing, and can’t account for your symptoms, scans or history.
References
- Rinella ME, et al. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology 2023. doi:10.1097/HEP.0000000000000323. natap.org (PDF)
- EASL, EASD and EASO. Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD). Diabetologia 2024 (also J Hepatol 2024). air.unimi.it (PDF)
- National Institute for Health and Care Excellence. Non-alcoholic fatty liver disease (NAFLD): assessment and management (NG49), 2016. nice.org.uk
- Health Technology Wales. ELF test (Enhanced Liver Fibrosis), GUI061, October 2024. healthtechnology.wales. BSG endorsement: bsg.org.uk
- Newsome PN, et al. Guidelines on the management of abnormal liver blood tests. Gut 2018;67:6–19. eprints.soton.ac.uk (PDF)
- Kanwal F, et al. AGA Clinical Care Pathway for NAFLD. Gastroenterology 2021. Summary: mdedge.com
- EASL Clinical Practice Guidelines on non-invasive tests for evaluation of liver disease severity and prognosis, 2021 update. J Hepatol 2021. easl.eu (PDF)
- Sterling RK, et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection. Hepatology 2006;43:1317–1325. scholars.mssm.edu
- Shah AG, et al. Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol 2009;7:1104–1112. scholars.duke.edu
- McPherson S, et al. Age as a confounding factor for the accurate non-invasive diagnosis of advanced NAFLD fibrosis. Am J Gastroenterol 2017;112:740–751. ncl.ac.uk
- Kwo PY, et al. ACG Clinical Guideline: Evaluation of abnormal liver chemistries. Am J Gastroenterol 2017;112:18–35. PDF
- South West London (Wandsworth and Merton). Community MASLD pathway, 2025. stgeorges.nhs.uk (PDF)
- British Liver Trust. What are the stages of MASLD? britishlivertrust.org.uk
- British Liver Trust. Symptoms of liver disease: red flag symptoms. britishlivertrust.org.uk
This page is for education only and isn’t medical advice, a diagnosis or a substitute for your own doctor. FIB-4 is a screening score, and cut-offs vary between guidelines and local pathways. Always interpret results with a qualified clinician. See our medical disclaimer.
