Ipv6 Ula Generator

Free online tool. All processing is client-side. No signup needed.

How to Use the Ipv6 Ula Generator

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Ipv6 Ula Generator?

An IPv6 ULA Generator creates RFC 4193-compliant Unique Local Addresses — the IPv6 equivalent of private IPv4 addresses (10.x, 192.168.x). ULAs start with 'fd' followed by a 40-bit random Global ID, making collision between independently generated ULA prefixes astronomically unlikely. They're ideal for internal enterprise networks, home labs, and IoT deployments.

How Does It Work?

Click Generate to create a ULA /48 prefix. The generator uses cryptographically secure randomness for the 40-bit Global ID, then formats the output as: (1) /48 prefix for your whole site, (2) /64 subnet example (standard subnet size), (3) a full example address. Each generation is unique; save your prefix for consistency.

Formula

ULA Format: fd + 40-bit Global ID (random) + 16-bit Subnet ID + 64-bit Interface ID\n/48 prefix: fdXX:XXXX:XXXX::/48\n/64 subnet: fdXX:XXXX:XXXX:YYYY::/64\nCollision probability (40 random bits): with 10,000 prefixes ≈ 0.005%

Who Uses This Tool?

• Network architects designing IPv6 addressing for enterprise intranets
• Home lab enthusiasts setting up IPv6 for isolated networks
• Dual-stack deployments: private IPv4 + ULA IPv6 for internal services
• IoT deployments needing private, collision-free addresses at scale
• Testing IPv6 applications without internet access

Pro Tips

• Generate your /48 prefix once and save it. Use it consistently across your organization for all internal IPv6 addressing
• ULA and Global Unicast Addresses (GUA) coexist: use GUA for internet-facing, ULA for internal-only services
• Unlike IPv4 private addresses, ULA doesn't need NAT — the addresses simply aren't routable on the public internet

Frequently Asked Questions about Ipv6 Ula Generator

Do I need IPv6 private addresses if I have NAT?

NAT is primarily an IPv4 workaround. IPv6 was designed to eliminate NAT. ULA provides private addressing for internal-only services without internet routability.

Can two organizations generate the same ULA prefix?

Theoretically possible but practically impossible. With 40 random bits, you'd need ~1 trillion prefixes for a 50% collision chance.

Free online Ipv6 Ula Generator — no signup, 100% client-side processing. All data stays in your browser.