IPv4 to IPv6 Converter

Converts an IPv4 address into every standard IPv6 representation — IPv4-mapped, full expansion, NAT64 — for the dual-stack transition work that's now just a normal part of network engineering rather than a future problem to worry about later.

The formats you'll actually run into

• IPv4-mapped (::ffff:x.x.x.x) — RFC 4291, used internally by dual-stack sockets to represent an IPv4 connection inside IPv6 application code. This is the one you'll see most often in logs and application-level networking code.
• NAT64 (64:ff9b::x.x.x.x) — RFC 6052's Well-Known Prefix, letting IPv6-only clients reach IPv4-only servers through a translation gateway.
• IPv4-compatible (::x.x.x.x) — deprecated, don't use it in anything new.

Why this stopped being optional

RIPE NCC ran out of IPv4 addresses to allocate back in 2019 — the last regional registry to hit that wall. IPv6 support is now standard across major cloud providers and ISPs, and dual-stack deployment (running both protocols side by side) is the practical default for anything being built now, not a forward-looking nice-to-have. Native IPv6 also removes NAT traversal from the equation entirely, which is a real, measurable performance win, not just a protocol-purity argument.

What this actually means day to day

If you're still designing purely IPv4-only infrastructure, that's a decision worth actively questioning rather than a neutral default — most tooling, cloud platforms and ISPs already handle dual-stack cleanly, and the migration only gets more disruptive the longer address space and routing decisions get built around IPv4 alone.