{"id":66651,"date":"2026-10-12T08:58:35","date_gmt":"2026-10-12T05:58:35","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=66651"},"modified":"2026-10-12T08:58:35","modified_gmt":"2026-10-12T05:58:35","slug":"fib-4-score-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/medical\/fib-4-score-calculator\/","title":{"rendered":"FIB-4 Score Calculator"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Estimate Liver Fibrosis Risk from Age, AST, ALT and Platelets<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"66651\" data-favorite-title=\"FIB-4 Score\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/medical\/fib-4-score-calculator\/\" data-favorite-excerpt=\"Calculate your FIB-4 score from age, AST, ALT and platelet count to estimate the risk of advanced liver fibrosis. Enter values from your routine blood test and get an instant risk category.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-flask\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/medical\/fib-4-score-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-66651\" data-post=\"66651\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field has-term\" id=\"input-1\"><label for=\"field-1\">Age<\/label><div class=\"term\">Age<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"age\" id=\"field-1\" aria-describedby=\"calc-unit-1 calc-info-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"18\" max=\"100\" value=\"55\"\/><div class=\"unit\" id=\"calc-unit-1\">years<\/div><small id=\"calc-info-1\">FIB-4 is validated in adults<\/small><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-2\">AST<\/label><div class=\"term\">AST<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"ast\" id=\"field-2\" aria-describedby=\"calc-info-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" max=\"10000\" value=\"45\"\/><div class=\"grid grid-cols-1\"><select id=\"field-3\" name=\"unit\" aria-label=\"Unit\"><option value=\"ul\" selected>U\/L<\/option><option value=\"ukat\">\u00b5kat\/L<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-2\">Aspartate aminotransferase from your blood test<\/small><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-4\">ALT<\/label><div class=\"term\">ALT<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"alt\" id=\"field-4\" aria-describedby=\"calc-info-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" max=\"10000\" value=\"50\"\/><div class=\"grid grid-cols-1\"><select id=\"field-5\" name=\"unit\" aria-label=\"Unit\"><option value=\"ul\" selected>U\/L<\/option><option value=\"ukat\">\u00b5kat\/L<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-4\">Alanine aminotransferase from your blood test<\/small><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-6\">Platelet count<\/label><div class=\"term\">PLT<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"platelet_count\" id=\"field-6\" aria-describedby=\"calc-unit-6 calc-info-6\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" max=\"1000\" value=\"180\"\/><div class=\"unit\" id=\"calc-unit-6\">\u00d710\u2079\/L<\/div><small id=\"calc-info-6\">Same numeric value in 10\u00b3\/\u00b5L (e.g. 180)<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"66651\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Your FIB-4 Result<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>FIB-4 score<\/span><span class=\"result-term\">FIB-4<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-2\"><span class=\"field-title\"><span>Fibrosis risk category<\/span><\/span><span class=\"field-value\" id=\"result-2\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-3\"><span class=\"field-title\"><span>What this means<\/span><\/span><span class=\"field-value\" id=\"result-3\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"66651\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>FIB-4 Score Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ \\text{FIB-4} = \\frac{\\text{Age} \\times \\text{AST}}{\\text{PLT} \\times \\sqrt{\\text{ALT}}} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(\\text{Age}\\) \u2014 age in years<\/li>\n<li>\\(\\text{AST}\\) \u2014 aspartate aminotransferase in U\/L<\/li>\n<li>\\(\\text{ALT}\\) \u2014 alanine aminotransferase in U\/L<\/li>\n<li>\\(\\text{PLT}\\) \u2014 platelet count in \u00d710\u2079\/L<\/li>\n<\/ul>\n<p>The formula combines age and liver enzymes in the numerator with platelets (which fall as fibrosis progresses) in the denominator, giving a single number that rises with the likelihood of advanced fibrosis.<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>FIB-4 Score \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a 55-year-old with AST of 45 U\/L, ALT of 50 U\/L and a platelet count of 180 \u00d710\u2079\/L.<\/p>\n<p>\\[ \\text{FIB-4} = \\frac{55 \\times 45}{180 \\times \\sqrt{50}} = \\frac{2475}{180 \\times 7.07} \\approx \\frac{2475}{1272.8} \\approx 1.94 \\]<\/p>\n<p><strong>Result:<\/strong> FIB-4 = 1.94 \u2014 intermediate risk. The score falls in the indeterminate range (1.45\u20133.25), so additional testing such as liver elastography is usually recommended to clarify the risk.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the FIB-4 Calculator<\/h2>\n<ol>\n<li>Enter your <strong>Age<\/strong> in years (the score is validated for adults aged 18\u2013100).<\/li>\n<li>Enter your <strong>AST<\/strong> value from your blood test and select the unit \u2014 U\/L or \u00b5kat\/L. If your lab reports \u00b5kat\/L, the calculator converts it automatically (1 \u00b5kat\/L = 60 U\/L).<\/li>\n<li>Enter your <strong>ALT<\/strong> value the same way, choosing the matching unit.<\/li>\n<li>Enter your <strong>Platelet count<\/strong> in \u00d710\u2079\/L. This is the same number your lab reports in 10\u00b3\/\u00b5L \u2014 for example, a lab value of \"180 \u00d710\u2079\/L\" or \"180 K\/\u00b5L\" is simply entered as 180.<\/li>\n<li>Read your <strong>FIB-4 score<\/strong>, the risk category, and an explanation of what the result means.<\/li>\n<\/ol>\n<h2>What Is the FIB-4 Score?<\/h2>\n<p>The FIB-4 index is a non-invasive fibrosis score built from four routine measurements: age, AST, ALT and platelet count. It was originally developed by Sterling and colleagues (Hepatology, 2006) in patients with HIV\/HCV coinfection and has since been widely validated in chronic hepatitis C, fatty liver disease (NAFLD\/MASLD) and other chronic liver conditions. Because it uses only standard blood work, it is often the first step in deciding whether a patient with abnormal liver enzymes needs further evaluation.<\/p>\n<p>The logic behind the formula is straightforward: liver enzymes (AST and ALT) tend to rise as the liver is damaged, while platelet count falls as fibrosis progresses \u2014 advanced scarring causes portal hypertension and splenic sequestration of platelets. Age adds weight because fibrosis accumulates over time. The result is a dimensionless number that increases with the likelihood of advanced fibrosis (stage F3\u2013F4 in the METAVIR classification).<\/p>\n<p>The standard interpretation uses two cut-offs: a score below <strong>1.45<\/strong> indicates low risk, a score above <strong>3.25<\/strong> indicates high risk of advanced fibrosis, and values in between are indeterminate. In the original validation cohorts, more than 90% of patients below 1.45 had no advanced fibrosis, while a score above 3.25 carried a high probability of significant scarring. An indeterminate result does not mean \"unknown\" \u2014 it means a second-line test (elastography, a proprietary fibrosis panel, or direct fibrosis markers) is warranted.<\/p>\n<h2>Interpreting Your Result<\/h2>\n<p>A <strong>low-risk<\/strong> result (FIB-4 &lt; 1.45) generally rules out advanced fibrosis, and no immediate specialist referral is needed. An <strong>intermediate<\/strong> result (1.45\u20133.25) calls for additional non-invasive testing rather than invasive procedures. A <strong>high-risk<\/strong> result (&gt; 3.25) usually prompts referral to a hepatologist, who may order liver elastography (FibroScan) or, in selected cases, a liver biopsy.<\/p>\n<p>Note that slightly different thresholds are used in fatty liver disease: many guidelines for NAFLD\/MASLD use <strong>1.3<\/strong> as the low-risk cut-off and <strong>2.67<\/strong> as the high-risk cut-off, because these values perform better in that population. If your result falls between the hepatitis C and NAFLD thresholds (for example 1.35 or 2.9), the calculator flags this in the interpretation.<\/p>\n<h2>Limitations and Practical Tips<\/h2>\n<ul>\n<li><strong>Age extremes:<\/strong> the score is less reliable in adults under 35 and over 65. In younger patients it tends to underestimate risk; in older patients it may overestimate it.<\/li>\n<li><strong>Not a diagnosis:<\/strong> FIB-4 is a screening tool, not a substitute for elastography, imaging or biopsy. It estimates probability, not certainty.<\/li>\n<li><strong>Other causes of abnormal values:<\/strong> thrombocytopenia from non-liver causes, acute hepatitis flares, or AST\/ALT elevations from muscle injury or intense exercise can distort the score.<\/li>\n<li><strong>Transient results:<\/strong> if your liver enzymes were elevated during an acute illness, it is worth recalculating the score once values have stabilized.<\/li>\n<li><strong>Not validated in:<\/strong> transplant recipients, patients on anticoagulants affecting platelet counts, or children.<\/li>\n<\/ul>\n<p>For a broader picture of liver-related risk, the <a href=\"https:\/\/wpcalc.com\/en\/medical\/meld-na-score-calculator\/\">MELD-Na Score<\/a> estimates short-term mortality in advanced liver disease, while the <a href=\"https:\/\/wpcalc.com\/en\/medical\/egfr-calculator-ckd-epi-2021\/\">eGFR calculator (CKD-EPI 2021)<\/a> and the <a href=\"https:\/\/wpcalc.com\/en\/medical\/ldl-cholesterol-calculator-friedewald\/\">LDL cholesterol calculator<\/a> help assess metabolic and cardiovascular factors that often accompany fatty liver disease. Always discuss your FIB-4 result with a healthcare professional who knows your full medical history.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Calculate your FIB-4 score from age, AST, ALT and platelet count to estimate the risk of advanced liver fibrosis. Enter values from your routine blood test and get an instant risk category.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[8],"tags":[50],"class_list":["post-66651","post","type-post","status-publish","format-standard","hentry","category-medical","tag-diagnostics"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66651","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/3168"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=66651"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66651\/revisions"}],"predecessor-version":[{"id":66652,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66651\/revisions\/66652"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=66651"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=66651"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=66651"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}