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IPv4 to IPv6 Converter: Mapped, 6to4 and NAT64 Forms

This free IPv4 to IPv6 converter shows how an IPv4 address looks in IPv6. Enter an address to see its IPv4-mapped, 6to4 and NAT64 forms in short and full notation. It runs in your browser.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is IPv4 to IPv6 Conversion?

IPv4 to IPv6 conversion means writing an IPv4 address in one of the standard IPv6 formats that carry an IPv4 address inside. There is no single “IPv6 version” of an IPv4 address. Several transition methods exist, and each one embeds the 32 bits of the IPv4 address in a different place.

These forms appear in server logs, socket software, firewall rules and migration plans. This tool shows the four common ones side by side, in short and full notation.

How to Use This IPv4 to IPv6 Converter

  1. Enter a valid IPv4 address, for example 192.0.2.33.
  2. Press Convert.
  3. Copy the form you need from the table.
  4. Use the full form when you must compare addresses or enter them in strict software.

The IPv6 Forms of an IPv4 Address

FormLooks likeUsed for
IPv4-mapped::ffff:192.0.2.33Dual-stack sockets that handle IPv4 clients as IPv6
IPv4-compatible::192.0.2.33Deprecated. Old tunnelling method, avoid it
6to42002:c000:0221::Automatic tunnels, now mostly retired
NAT6464:ff9b::192.0.2.33IPv6-only clients reaching IPv4 servers

The architecture behind these formats is set out in RFC 4291, the IPv6 addressing architecture.

Which Form Should I Use?

  • Reading logs: an address like ::ffff:203.0.113.9 is simply an IPv4 visitor, so treat it as 203.0.113.9.
  • Firewall rules on a dual-stack host: write rules for the IPv4 address itself, and check whether your firewall uses the mapped form.
  • Reaching IPv4 from an IPv6-only network: NAT64 with the prefix 64:ff9b::/96 is the standard approach.
  • New designs: avoid 6to4 and IPv4-compatible addresses.

Moving From IPv4 to IPv6

Converting an address is only a small part of an IPv6 move. You also need AAAA records, IPv6-aware firewalls and server settings. Test your domain with the IPv6 readiness test, and tidy long addresses with the IPv6 compression tool.

To go the other way and read the IPv4 address out of an IPv6 address, use the IPv6 to IPv4 converter. The conversion runs in your browser, and the address you type is not stored.

Common Questions About These Formats

People often ask why an IPv4 address is not simply the same address in IPv6. The two protocols are separate networks, so translation or tunnelling is needed to connect them. The mapped form helps software handle both kinds of client with one socket, while NAT64 and 6to4 help traffic cross between the networks.

Knowing which form you see in a log or a configuration file tells you how the traffic arrived and what to expect from it. When you design a network, pick one method on purpose and document it, because mixing methods without a plan is a common cause of hard-to-find faults.

Frequently Asked Questions

No. There are several standard ways to embed an IPv4 address in IPv6, each for a different purpose. This tool shows the four most common ones.
It is written ::ffff: followed by the IPv4 address. Dual-stack software uses it internally to treat IPv4 connections as IPv6 sockets.
A 6to4 address starts with 2002: and carries the IPv4 address in the next 32 bits. It was used for automatic tunnelling and is now mostly retired.
NAT64 lets IPv6-only clients reach IPv4 servers. The well-known prefix 64:ff9b::/96 holds the IPv4 address in its last 32 bits.

Disclaimer: results come from live requests and can change as records and servers change. We cannot guarantee that every answer matches what every visitor sees.