IPv4 to IPv6 Converter
Map any IPv4 address to its IPv6 equivalents: IPv4-mapped, IPv4-compatible, 6to4, Teredo, ISATAP, and NAT64 — in full, compressed, or mixed notation. Reverse any embedded IPv6 address back to IPv4, or convert a whole list at once.
Advanced: Teredo & ISATAP inputs
| Format | Prefix | IPv6 address |
|---|
| # | Input | Mapped | 6to4 | NAT64 | Status |
|---|
What each format means
::ffff:a.b.c.d
IPv4-mapped — ::ffff:0:0/96, RFC 4291 §2.5.5.2. Lets a dual-stack application handle IPv4 peers on an IPv6 socket. Example: 192.0.2.1 → ::ffff:192.0.2.1.
::a.b.c.d deprecated
IPv4-compatible — ::/96, RFC 4291. The old automatic-tunneling format; deprecated because it proved unworkable. Never use in new designs.
2002:WWXX:YYZZ::
6to4 — 2002::/16, RFC 3056. Embeds a public IPv4 address (in hex) after 2002:: to tunnel IPv6 over IPv4. 192.0.2.1 → 2002:c000:201::. Deprecated by RFC 7526.
2001:0:…
Teredo — 2001::/32, RFC 4380. Tunnels IPv6 over UDP through NAT, encoding server IPv4, flags, obfuscated port, and obfuscated client IPv4.
…:0:5EFE:w.x.y.z
ISATAP — RFC 5214. Intranet tunneling: interface identifier ::0:5EFE:w.x.y.z under your /64 prefix. 2001:db8::/64 + 192.0.2.1 → 2001:db8::5efe:c000:201.
64:ff9b::/96
NAT64 well-known prefix — RFC 6052. The prefix NAT64/DNS64 translators use so IPv6-only clients can reach IPv4 servers. 192.0.2.1 → 64:ff9b::192.0.2.1.
Worked examples
192.0.2.1 in every form
IPv4-mapped: ::ffff:192.0.2.1 (hex ::ffff:c000:201) · 6to4: 2002:c000:201:: · NAT64: 64:ff9b::192.0.2.1 · ISATAP (2001:db8::/64): 2001:db8::5efe:c000:201.
Teredo, fully worked
Server 192.0.2.1, client 203.0.113.7, UDP port 3544 (0x0DD8 → obfuscated 0xF227), flags 0x8000: 2001:0:c000:201:8000:f227:34ff:8ef8. Paste it into the IPv6 → IPv4 tab to decode it back.
Reverse lookup
2002:c000:201:: is a 6to4 address embedding 192.0.2.1 — the second and third groups (c000:0201) are the IPv4 address in hexadecimal.
Related tools (different jobs)
- IPv4 to Binary Converter — dotted quad to 32-bit binary with bit toggles.
- IP to Hex Converter — IPv4 address to hexadecimal notation.
- Octal to IP Converter — octal notation back to a dotted-quad IPv4 address.
- Subnet Mask Calculator — CIDR masks, network ranges, and usable hosts.
This page is the dedicated IPv4 → IPv6 transition-format converter: mapped, compatible, 6to4, Teredo, ISATAP, and NAT64, plus reverse extraction.
Frequently asked questions
What is the IPv6 equivalent of 192.0.2.1?
It depends on the transition mechanism. The IPv4-mapped form (RFC 4291) is ::ffff:192.0.2.1 (hex ::ffff:c000:201), used by dual-stack sockets. The 6to4 form (RFC 3056) is 2002:c000:201::. The NAT64 well-known prefix (RFC 6052) gives 64:ff9b::192.0.2.1. The converter above computes every form — pick the one your use case needs.
What is an IPv4-mapped IPv6 address?
An address in ::ffff:0:0/96 (RFC 4291, section 2.5.5.2): the first 80 bits are zero, the next 16 bits are ffff, and the last 32 bits are the IPv4 address. Example: 192.0.2.1 becomes ::ffff:192.0.2.1. Dual-stack applications use this format to represent IPv4 peers on IPv6 sockets; it is not a routable address on the IPv6 internet by itself.
What is 6to4 and how is the address built?
6to4 (RFC 3056) embeds a public IPv4 address after the 2002::/16 prefix: 2002:WWXX:YYZZ::/48, where WW.XX.YY.ZZ is the IPv4 address written in hexadecimal. Example: 192.0.2.1 becomes 2002:c000:201::. Note that 6to4 was deprecated for new deployments by RFC 7526 (2015) — prefer native IPv6 or a managed tunnel broker.
What is a Teredo IPv6 address?
Teredo (RFC 4380) tunnels IPv6 over UDP/IPv4 through NATs using the 2001::/32 prefix. The address encodes the Teredo server IPv4 address, flags, the obfuscated UDP port, and the obfuscated client IPv4 address (obfuscation is a bitwise NOT). Example: server 192.0.2.1, client 203.0.113.7, port 3544, flags 0x8000 gives 2001:0:c000:201:8000:f227:34ff:8ef8. This page also decodes Teredo addresses back into server, port, and client.
What is ISATAP?
ISATAP (RFC 5214) is an automatic tunneling mechanism for IPv4 intranets. It builds the interface identifier ::0:5EFE:w.x.y.z under a /64 prefix, so with the documentation prefix 2001:db8::/64, IPv4 192.0.2.1 becomes 2001:db8::5efe:c000:201. Enter your own /64 prefix in the advanced inputs to compute ISATAP addresses for your network.
What is the NAT64 well-known prefix?
64:ff9b::/96 (RFC 6052) is the well-known prefix that NAT64 translators use to synthesize IPv6 addresses from IPv4 ones: 192.0.2.1 becomes 64:ff9b::192.0.2.1 (hex 64:ff9b::c000:201). DNS64 resolvers hand these synthesized addresses to IPv6-only clients so they can reach IPv4-only servers through the translator.
Can I extract the original IPv4 address from an IPv6 address?
Yes, for the stateless encodings. Paste a mapped (::ffff:a.b.c.d), compatible (::a.b.c.d), 6to4 (2002:...), NAT64 (64:ff9b::...), or ISATAP (...:5efe:...) address into the IPv6 to IPv4 tab and the tool recovers the dotted quad — for example 2002:c000:201:: decodes to 192.0.2.1. Teredo client addresses and ports are obfuscated with bitwise NOT, which this tool reverses as well. Native IPv6 addresses contain no IPv4 to extract.
Why is the IPv4-compatible address (::/96) deprecated?
RFC 4291 deprecated the IPv4-compatible format (::a.b.c.d, for example ::192.0.2.1) because automatic tunneling based on it proved unworkable and a security risk. Use IPv4-mapped (::ffff:a.b.c.d) for dual-stack sockets, or a real transition mechanism such as native IPv6 or NAT64.
Is this converter private? Does it send my addresses anywhere?
Yes, it is fully private. Every conversion runs in JavaScript inside your browser — no address you type is sent to any server. You can disconnect from the network after the page loads and the tool keeps working.
Free tool by NRTechStudio