IPv4 to IPv6 Converter
Enter an IPv4 address and see how it sits inside IPv6: the IPv4-mapped ::ffff: form (in both hex and dotted notation), the deprecated IPv4-compatible form, and the 6to4 2002::/48 prefix.
0–255, separated by dots.
IPv4 and IPv6 are separate protocols, but IPv6 was designed with several ways to carry a 32-bit IPv4 address inside a 128-bit IPv6 address. This converter shows the three you are most likely to meet, so you can recognise them in logs, socket APIs and tunnel configurations.
The most common is the IPv4-mapped address, which lives in the ::ffff:0:0/96 block. It is written as ::ffff:c0a8:1 or, more readably, ::ffff:192.168.0.1. Dual-stack systems use it so a single IPv6 listening socket can accept IPv4 clients — when a `127.0.0.1` connection shows up in your logs as ::ffff:127.0.0.1, this is why.
IPv4-mapped (::ffff:192.168.0.1) is the modern, widely used form. 6to4 (2002:c0a8:1::/48) gives an IPv4-connected site an IPv6 prefix for transition tunnels. IPv4-compatible (::c0a8:1) is deprecated by RFC 4291 and shown only for decoding legacy configs.
The 6to4 form takes your IPv4 address and places it directly after the 2002::/16 prefix, producing a /48 that an entire site could use during IPv4-to-IPv6 transition. It is largely deprecated today but still appears in older documentation and tunnels. The IPv4-compatible form (a bare ::x.x.x.x) is fully deprecated and should never be used for new deployments.
Want the bigger picture? Our guide on IPv4 vs IPv6 compares the two protocols, and why IPv6 adoption is slow explains why transition mechanisms like these still matter. To normalise the resulting address, reach for the IPv6 Expand & Compress tool, or plan blocks with the IPv6 Subnet Calculator. Everything here runs locally — nothing is sent anywhere.
Frequently asked questions
What is an IPv4-mapped IPv6 address?
An IPv4-mapped IPv6 address embeds a 32-bit IPv4 address inside the ::ffff:0:0/96 prefix, written as ::ffff:c0a8:1 or the dotted form ::ffff:192.168.0.1. Dual-stack operating systems use this form so a single IPv6 socket can also accept IPv4 connections.
What is a 6to4 address?
6to4 embeds an IPv4 address into the 2002::/16 prefix so a site with a public IPv4 address can be reached over IPv6 without a native allocation. Your IPv4 becomes the next 32 bits, giving each site a 2002:IPv4::/48 block. 6to4 is now largely deprecated but still useful to understand.
Is the IPv4-compatible IPv6 format still used?
No. The IPv4-compatible format (::x.x.x.x, for example ::c0a8:1) was deprecated by RFC 4291. It is shown here for completeness and for decoding old configurations, but you should use IPv4-mapped or native IPv6 addresses instead.
Does converting change the underlying address?
No. These are different textual representations that embed the same 32-bit IPv4 value inside a 128-bit IPv6 address. The conversion is reversible and happens entirely in your browser.
Want the theory? Read the guides → · Visit the zoo →