IPv6 Subnet Calculator
Enter an IPv6 address with prefix (CIDR notation) to calculate subnet details
Try these examples:
What is IPv6?
IPv6 is the most recent version of the Internet Protocol, providing an identification and location system for computers on networks. It offers a significantly larger address space than IPv4, using 128-bit addresses.
IPv6 vs IPv4
Larger address space: 128-bit vs 32-bit
Built-in security: IPsec is mandatory
Simplified header: Improves packet handling
Subnetting Explained
Subnetting divides an IP network into sub-networks, improving security and performance. IPv6 subnetting uses prefix lengths rather than subnet masks to define networks.
The prefix length (like /64) indicates how many bits identify the network portion of the address, with the remaining bits available for host addresses.
Common Prefix Lengths
- /48 - Typical assignment to a customer site
- /56 - Typical assignment to a small customer site
- /64 - Standard subnet size for most networks
- /127 - Point-to-point links (like /31 in IPv4)
Advanced IPv6 Concepts
Address Types
IPv6 includes several address types including unicast (global, link-local, unique-local), multicast, and anycast addresses. Each serves different network functions.
IPv6 Address Structure
An IPv6 address consists of eight groups of four hexadecimal digits separated by colons. Leading zeros can be omitted and consecutive zero segments can be replaced with a double colon (::).
Example Address Breakdown:
| Full Address | Compressed | Prefix | Purpose |
|---|---|---|---|
| 2001:0db8:0000:0000:0000:0000:0000:0001 | 2001:db8::1 | /64 | Documentation |
| fe80:0000:0000:0000:0202:b3ff:fe1e:8329 | fe80::202:b3ff:fe1e:8329 | /64 | Link-local |
Frequently Asked Questions About IPv6 Subnetting
Why should I use IPv6?
IPv6 offers a significantly larger address space, built-in security features, improved routing efficiency, and eliminates the need for NAT. It's the future of internet addressing as we've exhausted the IPv4 address space.
What's the difference between IPv6 and IPv4 subnetting?
IPv6 uses prefix notation (like /64) rather than subnet masks. IPv6 subnetting is typically more straightforward, with standard allocations like /64 for most networks.
What prefix length should I use for my network?
For most end-user networks, /64 is the standard recommendation. ISPs typically allocate /48 or /56 to organizations, allowing for multiple /64 subnets.
Can I use both IPv4 and IPv6 simultaneously?
Yes, most networks operate in a dual-stack configuration during transition, allowing both protocols to function in parallel until a complete migration to IPv6 is possible.