Enter an IPv4 address to see how it is written inside IPv6 — the IPv4-mapped form, the 6to4 prefix and the NAT64 address. Or paste one of those to get the IPv4 address back.
Runs entirely in your browser — nothing you enter here is sent to a server.
IPv6 does not extend IPv4 — it is a separate address space, and an IPv4 address has no "equivalent" native IPv6 address. What exists instead are a few reserved IPv6 ranges whose last 32 bits carry an IPv4 address. Each has a specific job.
How a dual-stack program sees an IPv4 client on an IPv6 socket. It appears in server logs as ::ffff:203.0.113.5. Never sent on the wire.
Lets IPv6-only networks reach IPv4 servers through a translator. Used by mobile carriers together with DNS64.
An old automatic tunnel: every public IPv4 address got a /48. Deprecated, but still seen in logs.
The first attempt, ::192.0.2.1. Deprecated since 2006; shown here only so you can recognise it.
The most common is the IPv4-mapped form in application logs. A web server listening on [::]:80 with dual-stack sockets reports every IPv4 visitor as ::ffff:a.b.c.d. Rate limiters, geolocation lookups and allowlists that expect plain IPv4 then silently fail to match. Strip the ::ffff: prefix before comparing — or use this tool to read the address back.
NAT64 matters if you run an app used on mobile networks: an IPv6-only phone reaches your IPv4-only server as 64:ff9b:: plus your address. It works for names, through DNS64, but not for IPv4 literals hard-coded in the app — which is why Apple requires apps to work on IPv6-only networks.
You cannot turn it into a native IPv6 address — the two are different networks. You can write it in IPv4-mapped form by putting ::ffff: in front: 192.0.2.128 becomes ::ffff:192.0.2.128, or ::ffff:c000:280 in hex.
It is an IPv4-mapped IPv6 address: an IPv4 client seen by software that listens on an IPv6 socket. The real address is the part after ::ffff:.
Convert each of the four numbers to two hex digits and join them in pairs. 192.0.2.128 is c0, 00, 02, 80 — written as c000:0280, or c000:280 without the leading zero.
Usually yes, through the carrier's NAT64 and DNS64 — as long as visitors reach it by name. For reliable native IPv6 access the server needs its own IPv6 address and an AAAA record.
Upzilla checks that both of them open, from several locations, around the clock. 10 monitors free.