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IPv6 Subnet Calculator

Free online IPv6 subnet calculator: RFC 5952 compressed and expanded forms, network range, address count, and type detection (ULA, link-local, multicast).

Privacy: all processing happens locally in your browser. Your input never leaves your device.

What is IPv6 Subnet Calculator?

IPv6 addresses are long and come in many spellings — the same address can be compressed, expanded, or written in mixed case. This tool accepts compressed notation and embedded IPv4 (e.g. ::ffff:1.2.3.4), and outputs the RFC 5952 canonical compressed form plus the full 8-group expanded form. Given a prefix it computes the network address, first and last address, and total address count, and identifies the address type: loopback, link-local (fe80::/10), unique local (fc00::/7), multicast (ff00::/8), documentation (2001:db8::/32) and more. All computation is local.

How to Use

  1. Enter an IPv6 address or CIDR (e.g. 2001:db8::/32; a bare address defaults to /64)
  2. View the compressed/expanded forms, type and subnet range

FAQ

Does IPv6 subtract 2 from the usable host count?
No. IPv6 has no broadcast address (multicast replaces it), so every address in the block is assignable, including all-zeros and all-ones.
Why is the address count astronomical?
A /64 holds 2^64 ≈ 18.4 quintillion addresses — IPv6 was designed so every device can have a public address, eliminating the need for NAT.
Can an fe80:: address reach the internet?
No. fe80::/10 is link-local and only valid on the current network segment, similar to IPv4's 169.254.x.x.

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Last updated 2026-09-15