[{"data":1,"prerenderedAt":149},["ShallowReactive",2],{"page-en-root-tools/subnet-cheat-sheet":3},{"content":4,"isFallback":110,"alternates":148},{"id":5,"title":6,"body":7,"description":108,"extension":109,"heroDark":110,"keywords":111,"locale":112,"meta":113,"navigation":140,"path":141,"seo":142,"sitemap":143,"stem":145,"translationKey":146,"__hash__":147},"content/tools/subnet-cheat-sheet.md","Subnet & CIDR Cheat Sheet — Mask, Wildcard, Host Chart",{"type":8,"value":9,"toc":105},"minimark",[10,15,18,26,93,99],[11,12],"essential-hero3-section",{"description":13,"title":14},"Every IPv4 prefix from /32 to /0 — mask, wildcard, address count, usable hosts, and how big it is next to a /24. Plus the IPv6 prefixes that come up in a real allocation. Print it, or take the PDF.","The \u003Cspan class=\"kw-swipe-d\">subnet cheat sheet\u003C/span>",[16,17],"tools-subnet-cheat-sheet",{},[19,20],"essential-call-to-action-section",{":primaryButton":21,"subtitle":22,"title":23,"className":24},"{\"text\":\"Get Free Asset Management\",\"url\":\"/free-asset-tracking\"}","A prefix tells you how many devices fit. UNIO24 tells you which ones are actually there, who signed for them, and when the warranty runs out. Free IT asset management for unlimited users.","You know the mask. Do you know the box?",[25],"cta-tight-bottom",[27,28,29],"essential-content-section",{},[30,31,33,37,40,45,61,64,68,71,74,78,81,84],"template",{"v-slot:description":32},"",[34,35,36],"p",{},"Everyone memorises the /24 row and then re-derives the rest at three in the morning. That is the entire reason this page exists — not to teach subnetting, but to sit open in a tab while you work.",[34,38,39],{},"We sell asset-tracking software, so read the pitch above with a raised eyebrow. The table costs nothing and asks nothing.",[41,42,44],"h3",{"id":43},"reading-a-row","Reading a row",[34,46,47,48,52,53,56,57,60],{},"Take ",[49,50,51],"code",{},"/26",". The mask is ",[49,54,55],{},"255.255.255.192",", the wildcard is ",[49,58,59],{},"0.0.0.63",", and the block holds 64 addresses of which 62 can go on interfaces. Four of these fit inside a /24. That last column is the one worth internalising: network people size things in /24s the way builders think in metres, and \"a /26 is a quarter of a /24\" gets you further in a planning meeting than 255.255.255.192 ever will.",[34,62,63],{},"The wildcard column is not decoration. Cisco ACLs and OSPF network statements take the mask inverted, and inverting it by hand under time pressure is where the typos come from.",[41,65,67],{"id":66},"the-two-rows-most-charts-get-wrong","The two rows most charts get wrong",[34,69,70],{},"A /31 shows two usable hosts here, not zero. RFC 3021 made both addresses on a /31 assignable specifically so router-to-router links stop burning four addresses to carry a two-address conversation, and it has been standard since 2000. Plenty of published cheat sheets still print 0, because they were generated by subtracting network and broadcast from every row without thinking about it.",[34,72,73],{},"A /32 is a single host route — one address, one usable. It shows up in routing tables, loopback interfaces and firewall rules constantly, and \"0 usable hosts\" is equally wrong there.",[41,75,77],{"id":76},"about-the-ipv6-half","About the IPv6 half",[34,79,80],{},"Counting hosts in IPv6 is a category error. A /64 holds 18.4 quintillion addresses; whether 40 or 4,000 devices sit on it changes nothing you would plan around. So that table counts /64s instead, because the actual question is how many LANs your allocation gives you — a /56 gives 256, a /48 gives 65,536, and if your ISP handed you a single /64 for a site with more than one VLAN, that is the conversation to have with them.",[34,82,83],{},"One caveat worth stating plainly: SLAAC needs exactly a /64. Subnet an IPv6 LAN tighter than that to \"save space\" and stateless autoconfiguration stops working, and you have saved space in a protocol where space is the one thing nobody is short of.",[34,85,86,87,92],{},"Need the arithmetic done for a specific address rather than a table to read? The ",[88,89,91],"a",{"href":90},"/tools/subnet-calculator","subnet calculator"," takes an address and a mask and works it out, splits a block into subnets, and checks a pasted IP plan for overlaps.",[94,95],"essential-faq-section",{":contactLink":96,":faqs":97,"title":98},"{\"text\":\"Tracking the devices behind those subnets?\",\"callActionText\":\"Talk to sales\",\"url\":\"/contacts\"}","[{\"title\":\"Using the table\",\"items\":[{\"question\":\"Is there a PDF version?\",\"answer\":\"Yes — the Download PDF button generates one with the full IPv4 table as selectable text, not a screenshot. There is a CSV too if you would rather paste the rows into a spreadsheet, and the Print button gives you a clean page without the site chrome.\"},{\"question\":\"Why does /27 give 30 hosts and not 32?\",\"answer\":\"A /27 block holds 32 addresses, but the first is the network address and the last is the broadcast address, so 30 are left for interfaces. Every row from /30 up to /0 works the same way. The exceptions are /31 and /32.\"},{\"question\":\"What is the difference between a subnet mask and a wildcard mask?\",\"answer\":\"They are inverses of each other. 255.255.255.0 as a mask is 0.0.0.255 as a wildcard. Interfaces and routing tables want the mask; Cisco access lists and OSPF network statements want the wildcard, which is why both columns are here.\"}]},{\"title\":\"Planning\",\"items\":[{\"question\":\"Which prefix should I use for a normal office VLAN?\",\"answer\":\"A /24 unless you have a reason not to — 254 hosts, and the third octet reads as the VLAN number, which makes the whole plan legible at a glance. Go to /23 or /22 when a floor genuinely outgrows it, and to /27 or /26 for small segments like a printer or camera VLAN.\"},{\"question\":\"Can I use a /31 on a normal LAN?\",\"answer\":\"No. A /31 is for point-to-point links between two routers, where there is nothing to broadcast to. On a multi-access segment you need a broadcast address, so /30 is the floor.\"},{\"question\":\"Should I plan IPv6 the same way as IPv4?\",\"answer\":\"No, and trying to is the most common mistake. IPv4 planning is about conserving addresses; IPv6 planning is about keeping the structure readable. Give every LAN a /64 even when it holds three devices, and use the bits above it to encode site and function.\"}]}]","Subnetting — quick answers",[19,100],{":primaryButton":101,"subtitle":102,"title":103,":secondaryButton":104},"{\"text\":\"Start for Free\",\"url\":\"https://my.unio24.com/signup?utm_source=unio24-site&utm_medium=referral&utm_campaign=tools&utm_content=tools-subnet-cheat-sheet\"}","Start free with 50 assets: switches, access points and laptops in one place with owner, location, warranty and a QR tag that opens the record from a phone.","Every subnet eventually becomes an asset register","{\"text\":\"Book a Demo\",\"url\":\"/demo\"}",{"title":32,"searchDepth":106,"depth":106,"links":107},2,[],"Free subnet and CIDR cheat sheet: a chart of every IPv4 prefix from /32 to /0 with subnet mask, wildcard, address count and usable hosts, plus the IPv6 prefixes worth knowing. Printable, CSV and PDF.","md",false,"subnet cheat sheet, cidr cheat sheet, cidr chart, cidr table, subnetting cheat sheet, subnet mask chart, subnet table, ip subnet cheat sheet, subnet mask table, cidr notation chart, subnetting practice","en",{"schemaOrg":114},[115,126],{"@type":116,"name":117,"applicationCategory":118,"operatingSystem":119,"description":120,"url":121,"offers":122},"WebApplication","UNIO24 Subnet Cheat Sheet","BusinessApplication","Any","CIDR chart and subnet cheat sheet listing every IPv4 prefix from /32 to /0 with its subnet mask, wildcard mask, total addresses, usable hosts and size relative to a /24, plus common IPv6 prefixes, downloadable as PDF or CSV.","https://unio24.com/tools/subnet-cheat-sheet",{"@type":123,"price":124,"priceCurrency":125},"Offer","0","USD",{"@type":127,"itemListElement":128},"BreadcrumbList",[129,134,137],{"@type":130,"position":131,"name":132,"item":133},"ListItem",1,"Home","https://unio24.com/",{"@type":130,"position":106,"name":135,"item":136},"Tools","https://unio24.com/tools",{"@type":130,"position":138,"name":139,"item":121},3,"Subnet Cheat Sheet",true,"/tools/subnet-cheat-sheet",{"title":6,"description":108},{"loc":141,"lastmod":144},"2026-09-03T02:44:27+03:00","tools/subnet-cheat-sheet",null,"BZYBzQDlcfY8VOCoZXK0tN7ydJnT1JcmVk-u3ZAMOaY",[],1788397932278]