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Calculate IPv6 subnets, expansion, and compression. Use for IPv6 planning; for IPv4 use ipv4-subnet-calculator. Input: IPv6/CIDR. Returns subnet details. 100% client-side.
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Performs IPv6 address calculations in the browser. Expand, compress, sort, and summarize IPv6 addresses, compute the network prefix, and enumerate the range of hosts covered by a CIDR block. Applies the RFC 4291 rules for leading-zero removal, case mapping, and the double-colon compression.
IPv6 addresses are long and easy to mistype, and IPv6 subnets follow different rules than IPv4. Network engineers need a reliable tool to expand compressed addresses, derive the network and interface IDs, and understand how many addresses a prefix covers.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Network engineers planning IPv6 deployments, DevOps engineers writing firewall and routing configs, security analysts auditing address ranges, and students learning IPv6 addressing.
Paste an IPv6 address in the input field
View the expanded and compressed forms side by side
Optionally add a /prefix to compute the network and available hosts
Read the scope classification (global, unique-local, link-local)
Copy any result you need for your configuration
2001:0db8:0000:0000:0000:ff00:0042:8329 → compressed: 2001:db8::ff00:42:8329fe80::1 → link-local scope2001:db8::/48 → 2^80 available addressesfc00::/7 → unique-local (ULA) scope2001:db8:1:2::/64 → the network is 2001:db8:1:2:: and hosts span 2001:db8:1:2:0:0:0:0 through 2001:db8:1:2:ffff:ffff:ffff:ffffWhat is the double colon in IPv6?
It represents the longest run of trailing zero hextets and can appear only once in an address.
How many addresses are in a /48?
2^(128-48) = 2^80 addresses.
Does this tool validate addresses?
Yes, it rejects malformed addresses and unwanted cases with a clear error.
Is calculation local?
All processing happens in your browser; nothing is uploaded.
Authoritative specifications, standards, and in-depth reading for IPv6 Calculator.
Expanded
2001:0db8:0000:0000:0000:0000:0000:0001
Compressed
2001:db8::::1
Follows RFC 4291 and RFC 5952 addressing rules. All computation happens locally in your browser.
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