{"id":131,"date":"2026-08-20T18:44:27","date_gmt":"2026-08-20T18:44:27","guid":{"rendered":"https:\/\/netguide.io\/tools\/ipv6-subnet-calculator\/"},"modified":"2026-08-20T18:44:27","modified_gmt":"2026-08-20T18:44:27","slug":"ipv6-subnet-calculator","status":"publish","type":"post","link":"https:\/\/netguide.io\/tools\/en\/ipv6-subnet-calculator\/","title":{"rendered":"IPv6 Subnet Calculator"},"content":{"rendered":"<div id=\"netgu-3773814202\" 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-v6-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-v6-title { margin:0 0 15px 0; color:#2271b1; font-size:1.4rem; }\n.wp-v6-grid { display:grid; grid-template-columns:repeat(auto-fit, minmax(140px, 1fr)); gap:12px; margin-bottom:10px; }\n.wp-v6-input-group label { display:block; font-size:11px; font-weight:bold; margin-bottom:4px; text-transform:uppercase; color:#666; }\n.wp-v6-input-group input, .wp-v6-input-group select { width:100%; padding:8px; border:1px solid #ccc; border-radius:4px; box-sizing:border-box; }\n.wp-v6-checkbox-group { margin:15px 0; font-size:12px; display:flex; align-items:center; gap:8px; color:#666; }\n.wp-v6-note { font-size:12px; color:#666; margin-top:12px; min-height:1em; }\n.wp-v6-warn { color:#d63638; font-weight:bold; }\n.wp-v6-results { margin-top:20px; border-top:2px solid #eee; padding-top:15px; }\n.wp-v6-res-item { display:flex; justify-content:space-between; margin-bottom:6px; font-size:14px; gap:10px; }\n.wp-v6-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-v6-val { color:#2271b1; font-weight:bold; }\n.wp-v6-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-v6-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.wpV6L = {\"empty\":\"Address missing\",\"oneColon\":\"Only one \\\"::\\\" allowed\",\"tooMany\":\"Too many groups\",\"need8\":\"IPv6 needs 8 groups (or ::)\",\"badGroup\":\"Invalid hex group\",\"prefix\":\"Prefix must be 0\u2013128\"};<\/script>\n<div class=\"wp-v6-container\">\n  <h3 class=\"wp-v6-title\">IPv6 Subnet Calculator<\/h3>\n  <div class=\"wp-v6-grid\">\n    <div class=\"wp-v6-input-group\" style=\"grid-column:1\/-1;\"><label>IPv6 address<\/label><input type=\"text\" id=\"v6-addr\" value=\"2001:db8::1\" oninput=\"calcV6()\"><\/div>\n    <div class=\"wp-v6-input-group\"><label>Prefix length (\/)<\/label><input type=\"number\" id=\"v6-prefix\" value=\"64\" min=\"0\" max=\"128\" step=\"1\" oninput=\"calcV6()\"><\/div>\n  <\/div>\n  <div id=\"v6-err\" class=\"wp-v6-warn\" style=\"min-height:1em; margin:6px 0;\"><\/div>\n  <div id=\"v6-results\" class=\"wp-v6-results\">\n    <div class=\"wp-v6-res-item\"><span>Full (expanded):<\/span><span id=\"v6-expanded\" class=\"wp-v6-val\">\u2014<\/span><\/div>\n    <div class=\"wp-v6-res-item\"><span>Compressed:<\/span><span id=\"v6-compressed\">\u2014<\/span><\/div>\n    <div class=\"wp-v6-res-item wp-v6-total\"><span>Network:<\/span><span id=\"v6-network\">\u2014<\/span><\/div>\n    <div class=\"wp-v6-res-item\"><span>First address:<\/span><span id=\"v6-first\">\u2014<\/span><\/div>\n    <div class=\"wp-v6-res-item\"><span>Last address:<\/span><span id=\"v6-last\">\u2014<\/span><\/div>\n    <div class=\"wp-v6-res-item\"><span>Number of addresses:<\/span><span id=\"v6-count\">\u2014<\/span><\/div>\n    <div class=\"wp-v6-res-item\"><span>Contained \/64 networks:<\/span><span id=\"v6-sub64\">\u2014<\/span><\/div>\n  <\/div>\n<\/div>\n<script>\nfunction v6ToBig(str){\n  str=String(str).trim(); var zi=str.indexOf('%'); if(zi>=0) str=str.slice(0,zi);\n  if(str==='') throw new Error('empty');\n  var parts;\n  if(str.indexOf('::')>=0){\n    if(str.indexOf('::')!==str.lastIndexOf('::')) throw new Error('oneColon');\n    var seg=str.split('::'); var head=seg[0]===''?[]:seg[0].split(':'); var tail=seg[1]===''?[]:seg[1].split(':');\n    var missing=8-head.length-tail.length; if(missing<1) throw new Error('tooMany');\n    var zeros=[]; for(var z=0;z<missing;z++) zeros.push('0'); parts=head.concat(zeros).concat(tail);\n  } else { parts=str.split(':'); }\n  if(parts.length!==8) throw new Error('need8');\n  var big=0n;\n  for(var i=0;i<8;i++){ var g=parts[i]===''?'0':parts[i]; if(!\/^[0-9a-fA-F]{1,4}$\/.test(g)) throw new Error('badGroup'); big=(big<<16n)|BigInt(parseInt(g,16)); }\n  return big;\n}\nfunction v6Groups(big){ var g=[]; for(var k=0;k<8;k++){ g[k]=Number((big>>BigInt((7-k)*16))&0xffffn); } return g; }\nfunction v6Expand(big){ return v6Groups(big).map(function(x){ var s=x.toString(16); while(s.length<4)s='0'+s; return s; }).join(':'); }\nfunction v6Compress(big){ var gr=v6Groups(big); var best=-1,bestLen=0,cur=-1,curLen=0;\n  for(var i=0;i<8;i++){ if(gr[i]===0){ if(cur<0){cur=i;curLen=1;} else curLen++; if(curLen>bestLen){bestLen=curLen;best=cur;} } else {cur=-1;curLen=0;} }\n  var hex=gr.map(function(x){return x.toString(16);}); if(bestLen<2) return hex.join(':');\n  return hex.slice(0,best).join(':')+'::'+hex.slice(best+bestLen).join(':'); }\nfunction v6Sep(s){ return s.replace(\/\\B(?=(\\d{3})+(?!\\d))\/g,'.'); }\nfunction calcV6(){\n  var L=window.wpV6L||{};\n  var addrStr=document.getElementById('v6-addr').value;\n  var prefix=parseInt(document.getElementById('v6-prefix').value,10);\n  var err=document.getElementById('v6-err'); var box=document.getElementById('v6-results');\n  try{\n    if(!(prefix>=0&&prefix<=128)) throw new Error('prefix');\n    var addr=v6ToBig(addrStr);\n    var maskBits=128n-BigInt(prefix); var full=(1n<<128n)-1n; var hostMask=maskBits===0n?0n:(1n<<maskBits)-1n;\n    var mask=full^hostMask; var network=addr&mask; var last=network|hostMask;\n    var count=(1n<<maskBits).toString(); var sub64= prefix<=64 ? (1n<<BigInt(64-prefix)).toString() : null;\n    document.getElementById('v6-expanded').innerText=v6Expand(addr);\n    document.getElementById('v6-compressed').innerText=v6Compress(addr);\n    document.getElementById('v6-network').innerText=v6Compress(network)+'\/'+prefix;\n    document.getElementById('v6-first').innerText=v6Compress(network);\n    document.getElementById('v6-last').innerText=v6Compress(last);\n    document.getElementById('v6-count').innerText=v6Sep(count);\n    document.getElementById('v6-sub64').innerText= sub64===null?'\\u2014':v6Sep(sub64);\n    err.innerText=''; box.style.opacity='1';\n  }catch(e){ err.innerText='\\u26A0 '+((L[e.message])||e.message); box.style.opacity='0.35'; }\n}\ncalcV6();\n<\/script>\n\n\n<div id=\"netgu-3624812666\"><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 the IPv6 subnet calculator works<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">IPv6 addresses are 128 bits long and written as eight groups of four hexadecimal digits. The calculator breaks an address with its prefix into its parts \u2013 both fully written out and in the short \"::\" notation.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Expanded vs. compressed:<\/strong> <code>2001:db8::1<\/code> is the short form of <code>2001:0db8:0000:0000:0000:0000:0000:0001<\/code>. \"::\" replaces exactly one run of zero groups.<\/li>\n\n\n<li><strong>Network & address range:<\/strong> The prefix (e.g. \/64) separates the network from the interface part. First and last address span the range.<\/li>\n\n\n<li><strong>\/64 networks:<\/strong> A \/48 prefix contains 65,536 individual \/64 networks \u2013 the usual size of a customer subnet.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The calculation runs entirely in the browser using 128-bit arithmetic (BigInt); no data is transmitted.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Related calculators<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"\/tools\/en\/subnetz-ip-rechner\/\">Subnet & IP Calculator<\/a><\/li>\n\n\n<li><a href=\"\/tools\/en\/poe-power-budget-calculator\/\">PoE Power Budget Calculator<\/a><\/li>\n<\/ul>\n\n\n<div id=\"netgu-4258422626\" 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>Analyse an IPv6 address and prefix \u2013 expanded and compressed form, network, first\/last address, address count and \/64 subnets.<\/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-131","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\/131","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=131"}],"version-history":[{"count":0,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/posts\/131\/revisions"}],"wp:attachment":[{"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/media?parent=131"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/categories?post=131"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/netguide.io\/tools\/wp-json\/wp\/v2\/tags?post=131"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}