IPv6 Subnet Prefix & Address Expansion Calculator
Expand compressed 128-bit IPv6 CIDR blocks, calculate prefix ranges, and evaluate /64 subnets.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. No data is ever transmitted across the network.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
How to Use IPv6 Subnet Prefix & Address Expansion Calculator
Type an IPv6 address with prefix (e.g. 2001:db8:85a3::/48).
Review the full uncompressed 8-hextet representation.
Copy start/end network boundaries and /64 subnet counts.
Frequently Asked Questions
What is the standard IPv6 LAN subnet size?
RFC 4291 recommends /64 as the standard subnet prefix for all end-user LANs.
How many /64 subnets exist in a /48 site allocation?
A /48 allocation contains 2^(64-48) = 65,536 distinct /64 networks.
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