Try: , ,
- Address (compressed)
- 2001:db8:abcd:12::1
- Address (expanded)
- 2001:0db8:abcd:0012:0000:0000:0000:0001
- Network
- 2001:db8:abcd::/48
- Network (expanded)
- 2001:0db8:abcd:0000:0000:0000:0000:0000
- First address
- 2001:db8:abcd::
- Last address
- 2001:db8:abcd:ffff:ffff:ffff:ffff:ffff
- Addresses
- 2^80 (1.21 × 10^24)
- /64 subnets
- 65,536
- Type
- Documentation (2001:db8::/32)
How to use it
- Type an IPv6 address with a prefix length, such as 2001:db8:abcd::/48. Without a prefix, /64 is assumed.
- Read the network, the range, the number of /64 subnets and the address type.
- Choose a size under “Split into” to list the subnets, for example the /56s or /64s inside a /48.
What the result means
- Compressed is the canonical short form from RFC 5952: lowercase, no leading zeros, and the longest run of zero groups replaced by
::. - Expanded writes all eight groups with four digits each, which is easier to compare and sort.
- Network is the address with every bit after the prefix set to zero.
- First and last address bound the subnet. IPv6 has no broadcast address, so every address in the range is usable.
- /64 subnets is how many standard LAN-sized subnets fit. A /64 is the size used on almost every IPv6 LAN, because SLAAC (automatic addressing) needs 64 host bits.
- Type tells you what kind of address it is: global unicast (2000::/3), unique local (fc00::/7), link-local (fe80::/10), multicast, loopback or documentation (2001:db8::/32).
Frequently asked questions
How many /64 subnets are in a /48?
65,536. A /48 leaves 16 bits between the prefix and /64, and 2^16 = 65,536. ISPs often give businesses a /48 and home users a /56, which holds 256 /64s.
How do I compress an IPv6 address?
Drop leading zeros in each group, then replace the longest run of two or more all-zero groups with ::, once. 2001:0db8:0000:0000:0000:ff00:0042:8329 becomes 2001:db8::ff00:42:8329. Use lowercase letters.
Why is every IPv6 LAN a /64?
Stateless address autoconfiguration (SLAAC) builds a device's address from a 64-bit network prefix plus a 64-bit interface ID. Smaller subnets break SLAAC, so /64 is the standard size for any network with hosts.
Does IPv6 have a broadcast address?
No. IPv6 replaced broadcast with multicast, for example ff02::1 for all nodes on a link. So unlike IPv4, you don't subtract two addresses from each subnet.
What is fe80:: on my Mac?
A link-local address. Every IPv6 interface has one, created automatically, and it only works on the local network segment. You'll see it in ifconfig output as fe80::…%en0, where %en0 names the interface.