Is an IPv6 ULA the same as an IPv4 private address?

It serves a similar local-use role, but IPv6 ULA has its own RFC 4193 format and addressing practices.

Why does a locally assigned ULA start with fd?

RFC 4193 sets the local-assignment bit in fc00::/7, producing the currently defined fd00::/8 form.

Does the generator use my MAC or IP address?

No. It uses browser cryptographic random bytes and does not read or upload a hardware or IP identifier.

IPv6 Unique Local Address Generator

Generate an RFC 4193 locally assigned IPv6 /48 prefix and sample /64 subnet with browser cryptographic randomness.

Local browser processing

Addresses and calculation inputs stay in this browser. They are not uploaded, resolved, scanned, or sent to analytics.

Sample 16-bit subnet ID

Result

Enter values and run the tool to see the local result.

What an IPv6 ULA prefix is

An IPv6 unique local address is intended for local communication and is not expected to be routed on the public Internet. This generator creates the locally assigned fd00::/8 form with a random 40-bit Global ID, producing a /48 prefix and sample /64 subnet.

How to generate an IPv6 ULA

Choose a sample 16-bit subnet ID or keep zero.
Generate a fresh 40-bit Global ID using browser cryptographic randomness.
Copy the /48 site prefix, expanded form, or sample /64 subnet for local planning.

ULA planning boundaries

Random generation reduces collision risk but does not register the prefix or coordinate it across merged organizations. ULA is not a substitute for a globally routed prefix and does not create routing, DNS, or firewall configuration.

Related network tools

IPv6 Subnet Calculator MAC Address Generator

IPv6 ULA questions

Is an IPv6 ULA the same as an IPv4 private address?: It serves a similar local-use role, but IPv6 ULA has its own RFC 4193 format and addressing practices.
Why does a locally assigned ULA start with fd?: RFC 4193 sets the local-assignment bit in fc00::/7, producing the currently defined fd00::/8 form.
Can a ULA be routed on the public Internet?: It is intended for local communication and is not expected to be routed globally.
Does the generator use my MAC or IP address?: No. It uses browser cryptographic random bytes and does not read or upload a hardware or IP identifier.