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IPv4 to IPv6 Converter

Convert IPv4 addresses to IPv6 mapped and 6to4 formats, and compress or expand IPv6 addresses.

Runs in your browser. Nothing you add is uploaded.

What the IPv4 to IPv6 Converter does

As networks transition from IPv4 exhaustion to global IPv6 adoption, engineers frequently encounter dual-stack protocols, tunneling mechanisms, and hybrid socket communications. This tool translates IPv4 addresses into standard IPv6 formats, including IPv4-mapped addresses (RFC 4291) and 6to4 prefixes (RFC 3056), and provides an IPv6 expander/compressor with reverse DNS zone computation.

How to convert and expand IP addresses

  1. Select IPv4 to IPv6 Converter or IPv6 Expander & Compressor mode.
  2. For IPv4, enter any decimal dotted-quad address to generate mapped and 6to4 prefixes.
  3. For IPv6, enter any compressed or mixed address to expand it to the full 32-digit canonical format.
  4. Inspect integer and hexadecimal conversions alongside reverse DNS pointer records.
  5. Copy any generated format directly to your clipboard for firewall or DNS zone files.

The IPv4 to IPv6 Converter runs entirely in your browser — nothing you enter is uploaded, stored, or logged.

When to use it

Dual-Stack Socket Programming

Software developers writing networking code in Node.js, Go, or Python use IPv4-mapped IPv6 addresses (::ffff:192.0.2.1) to support both IPv4 and IPv6 clients through a single IPv6 listening socket.

Reverse DNS (PTR) Record Deployment

Generating PTR records in ip6.arpa requires reversing all 32 hex nibbles separated by dots. This tool computes the exact reverse string automatically.

Firewall Rule Normalization

Expanding compressed IPv6 addresses to 32 digits eliminates ambiguities when auditing access control lists and security group rules.

Good to know

  • RFC 5952 dictates that only the longest consecutive sequence of zero 16-bit blocks should be replaced by '::'.
  • IPv4-mapped addresses start with ::ffff: followed by the IPv4 address in decimal or hex.
  • 6to4 uses the 2002::/16 prefix, embedding the 32-bit IPv4 address into the next 32 bits.

Frequently asked questions

What is an IPv4-mapped IPv6 address?

An IPv4-mapped IPv6 address (formatted as ::ffff:a.b.c.d) allows dual-stack network applications to handle IPv4 traffic using IPv6 socket APIs transparently.

What is the 6to4 prefix standard?

RFC 3056 defines 6to4 as an automatic transition mechanism using the 2002::/16 prefix, embedding the 32-bit IPv4 address into the next 32 bits to provide a unique /48 IPv6 routing prefix.

What happened to IPv4-compatible IPv6 addresses?

IPv4-compatible addresses (::192.0.2.1 without ffff) were deprecated by RFC 4291 because they caused routing ambiguities. IPv4-mapped addresses (::ffff:192.0.2.1) should always be used instead.

Why does IPv6 use colons instead of dots?

IPv6 addresses are 128 bits long (represented as 8 groups of 4 hexadecimal digits). Dots are reserved for IPv4 and domain names, whereas colons provide a clean delimiter for 16-bit hex blocks.

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