Expand, compress and subnet IPv6 addresses with prefix and range details.
An IPv6 address is 128 bits, usually written as eight groups of four hex digits. The prefix length says how many leading bits identify the network. Applying the prefix mask gives the network address; the remaining host bits define the range from the first to the last address, for 2^(128 − prefix) total addresses. This calculator also shows the fully-expanded and RFC 5952-compressed forms.
Network address
network = ip AND mask, where mask is the top `prefix` bits set
Address count
count = 2^(128 − prefix)
IPv6 was designed so each LAN gets a /64, leaving 64 host bits. That's 18.4 quintillion addresses per subnet, which supports stateless address autoconfiguration (SLAAC).
A single '::' replaces the longest run of consecutive all-zero groups (at least two). It can appear only once in an address. This tool shows both the compressed and fully-expanded forms.
No. IPv6 has no broadcast address, and unlike IPv4 it doesn't reserve the first and last addresses of a subnet, so all 2^(128 − prefix) addresses in the block are usable in principle.