BYTETOOLS

IPv4 to IPv6 Converter

Convert an IPv4 address to its IPv4-mapped (::ffff:), IPv4-compatible and 6to4 IPv6 forms — or extract the IPv4 hidden inside an IPv6 address. Free and private.

IPv4-mapped IPv6 (the one you usually want)

::ffff:192.0.2.4

Used by dual-stack sockets and seen in server logs. Pure-hex form: ::ffff:c000:204

6to4 prefix (2002::/16)

2002:c000:204::/48

The /48 prefix this IPv4 address owns under the 6to4 transition scheme.

IPv4-compatible (deprecated)

::192.0.2.4

Deprecated by RFC 4291 — shown for completeness and for reading old configs.

What is the IPv4 to IPv6 Converter?

This converter produces every standard IPv6 representation of an IPv4 address: the IPv4-mapped form (::ffff:a.

  • IPv4-mapped output (::ffff:a.b.c.d) in both dotted and pure-hex form
  • 6to4 /48 prefix computed from the address's high and low 16 bits
  • Deprecated IPv4-compatible form shown for legacy configs, clearly labelled
  • Reverse mode extracts IPv4 from mapped, compatible and 6to4 addresses
  • Validates every octet and hextet before converting
  • 100% client-side — no DNS, no uploads

How to use the IPv4 to IPv6 Converter

  1. 1

    Choose the direction: IPv4 → IPv6 representations, or IPv6 → extract embedded IPv4.

  2. 2

    Enter the address to convert.

  3. 3

    Read the IPv4-mapped, 6to4 and IPv4-compatible forms — or the extracted IPv4 and which form it was found in.

  4. 4

    Copy any result with one click.

About the IPv4 to IPv6 Converter

This converter produces every standard IPv6 representation of an IPv4 address: the IPv4-mapped form (::ffff:a.b.c.d) used by dual-stack sockets and seen in server logs, the 6to4 prefix (2002:xxxx:xxxx::/48) derived from the address's 32-bit value, and the deprecated IPv4-compatible form kept for reading old configurations.

It also works in reverse: paste an IPv6 address and it detects whether it embeds an IPv4 address — mapped, compatible or 6to4 — and extracts the original dotted-quad. That is exactly what you need when a log file shows ::ffff:203.0.113.9 and you want the real client IP.

All conversions are simple bit arithmetic on the 32-bit address value, computed 100% locally in your browser. Nothing is uploaded, resolved or logged.

Frequently asked questions

Why does my server log show ::ffff: before an IPv4 address?

That is an IPv4-mapped IPv6 address. When a dual-stack server listens on an IPv6 socket, IPv4 clients appear as ::ffff:a.b.c.d. The connection is still plain IPv4 — strip the ::ffff: prefix (or use this tool's extract mode) to get the real client address.

How is an IPv4 address converted to IPv6?

There is no single conversion — IPv4 addresses are embedded in IPv6 in defined patterns. The mapped form puts the 32 bits after ::ffff:, and 6to4 puts them into the second and third hextets after the 2002: prefix. This tool shows all the standard embeddings at once.

What is a 6to4 address?

6to4 was a transition mechanism that gave every public IPv4 address an entire IPv6 /48 prefix: 2002: followed by the IPv4 address in hex. For example 192.0.2.4 owns 2002:c000:204::/48. It is largely historical now, but the prefixes still appear in the wild.

Is the IPv4-compatible format (::a.b.c.d) still used?

No — RFC 4291 deprecated it and modern systems do not generate it. This tool still shows and recognises it because you may encounter it in old documentation, configs or exam questions, and it is clearly labelled as deprecated.

Does this tool make my network IPv6-capable?

No. It converts address notation only — actually reaching IPv6 hosts requires your ISP or a tunnel to route IPv6 traffic. The tool is for reading logs, writing configs and understanding the address formats, entirely offline in your browser.

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