Ipv6 Subnet Calculator
Find a canonical IPv6 network address and an exact address count for the chosen prefix.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| IP address | valid IPv6 without zone ID |
| Prefix length | integer 0..128 |
Understanding your result
The output applies the selected format or address convention. Encoding is not encryption; a valid address representation does not establish availability, reachability or security.
Common mistakes
- Using a different alphabet, padding, base, delimiter or address-prefix convention than the tool expects.
Check your calculation
- Where a reverse operation exists, round-trip a short known example. Compare structural results with the reference example rather than executing decoded text.
Calculation checks, sources and review limits
What IPv6 network and exact address count belong to this prefix?
Find a canonical IPv6 network address and an exact address count for the chosen prefix.
Common uses
- Find a canonical IPv6 network address and an exact address count for the chosen prefix.
How it works
Parse 128-bit IPv6; network=(ip >> (128-prefix)) << (128-prefix); size=2^(128-prefix)
Worked example
Enter IP address: 2001:db8:1:2::1234; Prefix length: 64. The result is Network: 2001:db8:1:2::; Address count: 18446744073709551616.
FAQ
What IPv6 network and exact address count belong to this prefix?
Parse 128-bit IPv6; network=(ip >> (128-prefix)) << (128-prefix); size=2^(128-prefix)
What assumptions and limits apply?
IPv6 has no broadcast; counts are address-space sizes, not assignable host guarantees. Use BigInt and RFC5952 output.