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IPv6 Subnet Calculator

Calculate IPv6 network boundaries, address counts and practical subnet divisions from any IPv6 prefix.

Enter an IPv6 address and prefix, for example 2001:db8:1234::/48. Host bits are normalised to the network address.

IPv6 subnetting notes

/64 is the normal subnet size for SLAAC-capable LANs. A /48 provides 65,536 /64s, while a /56 provides 256 /64s. This calculator supports the full /0–/128 prefix range, but very large subnet expansions are deliberately capped in the displayed list.