{"id":139,"date":"2026-08-20T18:44:31","date_gmt":"2026-08-20T18:44:31","guid":{"rendered":"https:\/\/netguide.io\/tools\/password-entropy-calculator\/"},"modified":"2026-08-20T18:44:31","modified_gmt":"2026-08-20T18:44:31","slug":"password-entropy-calculator","status":"publish","type":"post","link":"https:\/\/netguide.io\/tools\/en\/password-entropy-calculator\/","title":{"rendered":"Password Entropy Calculator"},"content":{"rendered":"<div id=\"netgu-3508807618\" 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-pe-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-pe-title { margin:0 0 15px 0; color:#2271b1; font-size:1.4rem; }\n.wp-pe-grid { display:grid; grid-template-columns:repeat(auto-fit, minmax(140px, 1fr)); gap:12px; margin-bottom:10px; }\n.wp-pe-input-group label { display:block; font-size:11px; font-weight:bold; margin-bottom:4px; text-transform:uppercase; color:#666; }\n.wp-pe-input-group input, .wp-pe-input-group select { width:100%; padding:8px; border:1px solid #ccc; border-radius:4px; box-sizing:border-box; }\n.wp-pe-checkbox-group { margin:15px 0; font-size:12px; display:flex; align-items:center; gap:8px; color:#666; }\n.wp-pe-note { font-size:12px; color:#666; margin-top:12px; min-height:1em; }\n.wp-pe-warn { color:#d63638; font-weight:bold; }\n.wp-pe-results { margin-top:20px; border-top:2px solid #eee; padding-top:15px; }\n.wp-pe-res-item { display:flex; justify-content:space-between; margin-bottom:6px; font-size:14px; gap:10px; }\n.wp-pe-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-pe-val { color:#2271b1; font-weight:bold; }\n.wp-pe-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-pe-btn { background:#2271b1; color:#fff; border:none; padding:9px 14px; border-radius:4px; cursor:pointer; font-size:13px; margin-top:10px; }\n<\/style><script>window.wpPeL = {\"s1\":\"Very weak\",\"s2\":\"Weak\",\"s3\":\"Reasonable\",\"s4\":\"Strong\",\"s5\":\"Very strong\",\"years\":\"yrs\",\"days\":\"days\",\"hours\":\"hrs\",\"min\":\"min\",\"sec\":\"sec\"};<\/script>\n<div class=\"wp-pe-container\">\n  <h3 class=\"wp-pe-title\">Password Entropy Calculator<\/h3>\n  <div class=\"wp-pe-grid\">\n    <div class=\"wp-pe-input-group\" style=\"grid-column:1\/-1;\"><label>Password<\/label><input type=\"text\" id=\"pe-pass\" value=\"\" placeholder=\"Enter password\u2026\" oninput=\"calcEntropy()\"><\/div>\n  <\/div>\n  <div class=\"wp-pe-results\">\n    <div class=\"wp-pe-res-item\"><span>Length (characters):<\/span><span id=\"pe-len\">0<\/span><\/div>\n    <div class=\"wp-pe-res-item\"><span>Character space size:<\/span><span id=\"pe-pool\">0<\/span><\/div>\n    <div class=\"wp-pe-res-item wp-pe-total\"><span>Entropy:<\/span><span id=\"pe-bits\">0 bit<\/span><\/div>\n    <div class=\"wp-pe-res-item\"><span>Rating:<\/span><span id=\"pe-strength\">\u2014<\/span><\/div>\n    <div class=\"wp-pe-res-item\"><span>Estimated time to crack:<\/span><span id=\"pe-crack\">\u2014<\/span><\/div>\n  <\/div>\n  <div class=\"wp-pe-note\">Calculation assumes random characters (length \u00d7 log\u2082 character space). Real words\/patterns are weaker. Crack time at 10 billion guesses\/sec. All local \u2013 no password leaves the browser.<\/div>\n<\/div>\n<script>\nfunction peHuman(s,L){\n  if(!isFinite(s)) return '\\u221E';\n  if(s<1) return '< 1 '+(L.sec||'s');\n  var u=[[31557600,L.years||'a'],[86400,L.days||'d'],[3600,L.hours||'h'],[60,L.min||'min'],[1,L.sec||'s']];\n  for(var i=0;i<u.length;i++){ if(s>=u[i][0]){ var v=s\/u[i][0]; return (v>=1000? v.toExponential(2): v.toFixed(1))+' '+u[i][1]; } }\n  return '< 1 '+(L.sec||'s');\n}\nfunction calcEntropy(){\n  var pw=document.getElementById('pe-pass').value; var L=window.wpPeL||{};\n  var size=0;\n  if(\/[a-z]\/.test(pw)) size+=26;\n  if(\/[A-Z]\/.test(pw)) size+=26;\n  if(\/[0-9]\/.test(pw)) size+=10;\n  if(\/[^a-zA-Z0-9]\/.test(pw)) size+=33;\n  var bits= (pw.length>0 && size>0) ? pw.length*Math.log2(size) : 0;\n  document.getElementById('pe-len').innerText=pw.length+'';\n  document.getElementById('pe-pool').innerText=size+'';\n  document.getElementById('pe-bits').innerText=bits.toFixed(1)+' bit';\n  var label,color;\n  if(bits<28){label=L.s1;color='#d63638';}\n  else if(bits<36){label=L.s2;color='#d98a00';}\n  else if(bits<60){label=L.s3;color='#d98a00';}\n  else if(bits<128){label=L.s4;color='#2e7d32';}\n  else {label=L.s5;color='#2e7d32';}\n  var st=document.getElementById('pe-strength'); st.innerText=label||''; st.style.color=color;\n  var seconds=Math.pow(2,bits)\/2\/1e10;\n  document.getElementById('pe-crack').innerText=peHuman(seconds,L);\n}\ncalcEntropy();\n<\/script>\n\n\n<div id=\"netgu-13050484\"><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\">How password entropy is calculated<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Entropy measures the unpredictability of a password in bits. The more bits, the more attempts an attacker needs on average. The formula: length \u00d7 logarithm base 2 of the character-space size.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Character space:<\/strong> lowercase (26) + uppercase (26) + digits (10) + symbols (~33). The more classes, the larger the space.<\/li>\n\n\n<li><strong>Rule of thumb:<\/strong> Below 28 bits very weak, from 60 bits strong, from 128 bits very strong.<\/li>\n\n\n<li><strong>Limitation:<\/strong> The calculation assumes true randomness. \"Password123!\" has many bits on paper but is easily cracked by dictionary attacks.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For strong, random passwords, use our password generator or XKCD passphrase generator.<\/p>\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\/password-generator\/\">Password Generator<\/a><\/li>\n\n\n<li><a href=\"\/tools\/en\/xkcd-passphrase-generator\/\">XKCD Passphrase Generator<\/a><\/li>\n<\/ul>\n\n\n<div id=\"netgu-2577569429\" 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>Calculate password strength as entropy in bits \u2013 including character space and estimated time to crack. 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":[158],"tags":[],"class_list":["post-139","post","type-post","status-publish","format-standard","hentry","category-rechner-calculator-en"],"brizy_media":[],"_links":{"self":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/posts\/139","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=139"}],"version-history":[{"count":0,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/posts\/139\/revisions"}],"wp:attachment":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/media?parent=139"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/categories?post=139"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/tags?post=139"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}