Convert IPv4 to IPv6 representations, or expand and compress any IPv6 address. Results update as you type.
There is no one-to-one conversion. IPv4 and IPv6 are separate address spaces, and a host gets its IPv6 address from its network, not from its IPv4 address. What exists are standard ways to write an IPv4 address inside IPv6, each for one purpose, and this tool shows them all.
Take 192.0.2.33. As an IPv4-mapped address it is ::ffff:c000:221 (also written ::ffff:192.0.2.33): the form a dual-stack system uses to show an IPv4 client on an IPv6 socket. Its 6to4 prefix is 2002:c000:221::/48, the block a 6to4 router would have used for it. Neither gives the host a working IPv6 address on the Internet; for that its network needs IPv6 from the provider.
IPv4-mapped IPv6 (::ffff:x.x.x.x) is how dual-stack operating systems represent an IPv4 connection inside an IPv6 socket. When a server listens on an IPv6 socket with IPV6_V6ONLY disabled, incoming IPv4 clients appear as ::ffff:<their-ip>.
6to4 (2002::/16) is a transition mechanism that embeds an IPv4 address in the first 32 bits after the 2002: prefix, giving a /48 block to each IPv4 address. It is largely deprecated in favour of native IPv6 or other tunnels like Teredo.
IPv6 compression follows RFC 5952: leading zeros in each group are dropped, and the longest consecutive run of all-zero groups is replaced by :: (used at most once per address).