{"id":245,"date":"2026-08-21T18:30:34","date_gmt":"2026-08-21T18:30:34","guid":{"rendered":"https:\/\/netguide.io\/tools\/credit-card-luhn-checker\/"},"modified":"2026-08-21T18:30:34","modified_gmt":"2026-08-21T18:30:34","slug":"credit-card-luhn-checker","status":"publish","type":"post","link":"https:\/\/netguide.io\/tools\/en\/credit-card-luhn-checker\/","title":{"rendered":"Credit Card Checker (Luhn)"},"content":{"rendered":"<div id=\"netgu-3083470920\" class=\"netgu-before-content netgu-entity-placement\"><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-6258556257245998\" crossorigin=\"anonymous\"><\/script><ins class=\"adsbygoogle\" style=\"display:block;\" data-ad-client=\"ca-pub-6258556257245998\" \ndata-ad-slot=\"3494115342\" \ndata-ad-format=\"auto\"><\/ins>\n<script> \n(adsbygoogle = window.adsbygoogle || []).push({}); \n<\/script>\n<\/div>\n<style>\n.wp-luhn-container { max-width:100%; background:#fff; padding:20px; border:1px solid #ddd; border-radius:10px; font-family:-apple-system, sans-serif; color:#333; }\n.wp-luhn-title { margin:0 0 15px 0; color:#2271b1; font-size:1.4rem; }\n.wp-luhn-grid { display:grid; grid-template-columns:repeat(auto-fit, minmax(140px, 1fr)); gap:12px; margin-bottom:10px; }\n.wp-luhn-input-group label { display:block; font-size:11px; font-weight:bold; margin-bottom:4px; text-transform:uppercase; color:#666; }\n.wp-luhn-input-group input, .wp-luhn-input-group select { width:100%; padding:8px; border:1px solid #ccc; border-radius:4px; box-sizing:border-box; }\n.wp-luhn-checkbox-group { margin:15px 0; font-size:12px; display:flex; align-items:center; gap:8px; color:#666; }\n.wp-luhn-note { font-size:12px; color:#666; margin-top:12px; min-height:1em; }\n.wp-luhn-warn { color:#d63638; font-weight:bold; }\n.wp-luhn-results { margin-top:20px; border-top:2px solid #eee; padding-top:15px; }\n.wp-luhn-res-item { display:flex; justify-content:space-between; margin-bottom:6px; font-size:14px; gap:10px; }\n.wp-luhn-total { font-weight:bold; font-size:18px; color:#2271b1; margin:10px 0; padding:5px 0; border-top:1px solid #eee; border-bottom:1px solid #eee; }\n.wp-luhn-val { color:#2271b1; font-weight:bold; }\n.wp-luhn-out { width:100%; box-sizing:border-box; padding:10px; border:1px solid #ccc; border-radius:4px; font-family:monospace; font-size:13px; word-break:break-all; background:#f7f7f7; margin-top:6px; }\n.wp-luhn-btn { background:#2271b1; color:#fff; border:none; padding:9px 14px; border-radius:4px; cursor:pointer; font-size:13px; margin-top:10px; }\n<\/style><style>.wp-luhn-res{padding:12px;border-radius:6px;font-size:15px;font-weight:bold;margin-top:12px;background:#f9f9f9;border:1px solid #eee;min-height:1em;}.wp-luhn-res.ok{background:#e7f7ed;color:#2e7d32;border-color:#a5d6a7;}.wp-luhn-res.bad{background:#fdf2f2;color:#d32f2f;border-color:#ef9a9a;}<\/style><script>window.wpLuhnL = {\"waiting\":\"Enter number\u2026\",\"digits\":\"Digits only\",\"type\":\"Type\",\"digitsN\":\"digits\",\"valid\":\"Valid (Luhn check passed)\",\"invalid\":\"Invalid (Luhn check failed)\"};<\/script>\n<div class=\"wp-luhn-container\">\n  <h3 class=\"wp-luhn-title\">Credit Card Checker (Luhn)<\/h3>\n  <div class=\"wp-luhn-input-group\"><label>Number<\/label><input type=\"text\" id=\"luhn-in\" value=\"4539 1488 0343 6467\" oninput=\"luhnCheck()\"><\/div>\n  <div id=\"luhn-res\" class=\"wp-luhn-res\"><\/div>\n  <div id=\"luhn-det\" class=\"wp-luhn-note\" style=\"margin-top:8px;\"><\/div>\n  <div class=\"wp-luhn-note\">The Luhn test detects typos but says nothing about whether the card is valid or funded. All local \u2013 no transmission.<\/div>\n<\/div>\n<script>\nfunction luhnValid(n){ n=String(n).replace(\/\\s\/g,''); if(!\/^[0-9]+$\/.test(n))return false; var sum=0,alt=false; for(var i=n.length-1;i>=0;i--){ var d=parseInt(n[i],10); if(alt){ d=d*2; if(d>9)d-=9; } sum+=d; alt=!alt; } return sum%10===0; }\nfunction luhnCard(n){ n=n.replace(\/\\s\/g,''); if(\/^4\/.test(n))return 'Visa'; if(\/^(5[1-5]|2[2-7])\/.test(n))return 'Mastercard'; if(\/^3[47]\/.test(n))return 'American Express'; if(\/^6(011|5)\/.test(n))return 'Discover'; if(\/^3(0[0-5]|[68])\/.test(n))return 'Diners Club'; return '-'; }\nfunction luhnCheck(){\n  var raw=document.getElementById('luhn-in').value; var s=String(raw).replace(\/\\s\/g,''); var box=document.getElementById('luhn-res'); var det=document.getElementById('luhn-det'); var L=window.wpLuhnL||{};\n  if(!s){ box.className='wp-luhn-res'; box.innerText=L.waiting||''; det.innerText=''; return; }\n  if(!\/^[0-9]+$\/.test(s)){ box.className='wp-luhn-res bad'; box.innerText='\\u2717 '+(L.digits||'Digits only'); det.innerText=''; return; }\n  var ok=luhnValid(s);\n  det.innerText=(L.type||'Type')+': '+luhnCard(s)+'  \\u00b7  '+s.length+' '+(L.digitsN||'digits');\n  if(ok){ box.className='wp-luhn-res ok'; box.innerText='\\u2713 '+(L.valid||'Valid (Luhn check passed)'); }\n  else { box.className='wp-luhn-res bad'; box.innerText='\\u2717 '+(L.invalid||'Invalid (Luhn check failed)'); }\n}\nluhnCheck();\n<\/script>\n\n\n<div id=\"netgu-4168765150\"><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-6258556257245998\"\r\n     crossorigin=\"anonymous\"><\/script>\r\n<!-- NetGuide.io-After-Widget-Tools -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:block\"\r\n     data-ad-client=\"ca-pub-6258556257245998\"\r\n     data-ad-slot=\"5175852350\"\r\n     data-ad-format=\"auto\"\r\n     data-full-width-responsive=\"true\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">The Luhn algorithm<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Credit card numbers (and many other ID numbers) contain a check digit based on the Luhn method. It helps detect transposed digits and typos. The checker also shows the detected card type from the leading digits.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Luhn check:<\/strong> Every second digit is doubled (digit sum if &gt; 9), everything is summed \u2013 the total must be divisible by 10.<\/li>\n\n\n<li><strong>Card type:<\/strong> Detection of Visa, Mastercard, American Express, Discover and Diners Club.<\/li>\n\n\n<li><strong>Important:<\/strong> The test only checks the check digit, not the actual validity of the card.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Related tools<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"\/tools\/en\/iban-validator\/\">IBAN Validator<\/a><\/li>\n\n\n<li><a href=\"\/tools\/en\/password-leak-check\/\">Password Leak Check<\/a><\/li>\n<\/ul>\n\n\n<div id=\"netgu-3728794155\" class=\"netgu-after-content netgu-entity-placement\"><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-6258556257245998\" crossorigin=\"anonymous\"><\/script><ins class=\"adsbygoogle\" style=\"display:block;\" data-ad-client=\"ca-pub-6258556257245998\" \ndata-ad-slot=\"4559785002\" \ndata-ad-format=\"auto\"><\/ins>\n<script> \n(adsbygoogle = window.adsbygoogle || []).push({}); \n<\/script>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Check credit card or other numbers via the Luhn algorithm \u2013 including card type detection. Runs locally in the browser.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[131],"tags":[],"class_list":["post-245","post","type-post","status-publish","format-standard","hentry","category-validator-en"],"brizy_media":[],"_links":{"self":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/posts\/245","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/comments?post=245"}],"version-history":[{"count":0,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/posts\/245\/revisions"}],"wp:attachment":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/media?parent=245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/categories?post=245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/tags?post=245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}