Calculating IPv6 details...
Ready to calculate
Enter an IPv6 address or prefix to expand, classify, or subnet it.
IPv6 Address Calculator
The IPv6 Address Calculator expands compressed IPv6 notation, compresses full IPv6 addresses, calculates IPv6 prefix ranges, and splits IPv6 allocations into child subnets. It is designed for practical IPv6 planning, especially common `/64`, `/56`, `/48`, `/127`, and `/128` workflows.
Compressed vs Expanded IPv6
An IPv6 address has 128 bits written as eight hexadecimal groups called hextets. Expanded notation writes every hextet with four hexadecimal digits. Compressed notation removes leading zeroes and uses `::` for one run of zero hextets.
IPv6 Prefix Length Explained
An IPv6 prefix length says how many leftmost bits identify the network. The remaining bits identify addresses inside that prefix. For example, `/64` has 64 network bits and 64 host bits, which means it contains `2^64` addresses.
Common IPv6 Subnet Sizes
| Prefix | Common use | Addresses |
|---|---|---|
/48 | Site allocation | 2^80 |
/56 | Small-site or residential delegation | 2^72 |
/64 | Standard SLAAC LAN subnet | 2^64 |
/127 | Point-to-point link | 2 |
/128 | Single address or host route | 1 |
Why /64 Matters
Many IPv6 LAN designs use `/64` because Stateless Address Autoconfiguration expects a 64-bit interface identifier. Smaller LAN prefixes may work in controlled environments, but they can break assumptions in hosts, routers, and network tools.
IPv6 Address Types
IPv6 includes global unicast addresses, unique local addresses, link-local addresses, multicast addresses, loopback, unspecified, documentation space, and IPv4-mapped IPv6 notation. Classification helps avoid accidentally treating documentation, private, or link-local addresses as globally reachable.
Related Tools
- CIDR Notation Calculator for mixed IPv4 and IPv6 CIDR compare, split, and summarize workflows.
- Subnet Calculator for visual IPv4 subnet ranges and masks.
- IP Address Lookup for public IP address and location checks.
- DNS Record Lookup for A, AAAA, MX, NS, TXT, CNAME, and PTR records.
References
- RFC 4291 IPv6 Addressing Architecture
- RFC 5952 IPv6 text representation
- ARIN IPv6 information
- RIPE IPv6 basics
FAQ
What is an IPv6 address calculator?
It is a tool that expands, compresses, classifies, and calculates ranges for IPv6 addresses and prefixes.
How many addresses are in an IPv6 /64?
An IPv6 `/64` contains `18,446,744,073,709,551,616` addresses, which is `2^64`.
What is the difference between compressed and expanded IPv6?
Expanded IPv6 writes all eight four-digit hextets. Compressed IPv6 removes leading zeroes and may replace one zero run with `::`.
Does IPv6 have a broadcast address?
No. IPv6 does not use broadcast addresses. Multicast and neighbor discovery replace many IPv4 broadcast behaviors.
What is an IPv6 /128?
An IPv6 `/128` identifies exactly one IPv6 address, similar to a host route.