IPv6 Calculator

Enter an IPv6 address and a prefix length to expand or compress it and see the network, address range, and type - calculated instantly in your browser.

Compressed

Expanded (full)

Network / prefix

First address

Last address

Addresses in block

Address type

Expanding and compressing IPv6

An IPv6 address is 128 bits, written as eight groups of four hex digits. Because that's long, the notation allows two shortcuts: drop leading zeros in each group, and replace one run of all-zero groups with ::. So 2001:0db8:0000:0000:0000:0000:0000:0001 compresses to 2001:db8::1. The :: can only appear once, since otherwise the address would be ambiguous.

Prefixes and subnets

The prefix length (like /64) marks how many leading bits are the network portion. Home networks almost always get a /64 for each LAN - that's 18 quintillion addresses per subnet, enough that devices can pick their own addresses automatically (SLAAC). ISPs commonly delegate a /56 or /48 to a home, giving you many /64 subnets to work with.

Working in IPv4 instead? Use the subnet calculator or the CIDR cheat sheet.