IPv6 Subnet Calculator
See the range of an IPv6 prefix, how many /64 networks it holds, and split it.
IPv4 or IPv6; a prefix or mask typed after the address wins.
Calculate an IPv6 Prefix
IPv6 addresses are too long to work out by hand. This page opens the Subnet Calculator with an IPv6 prefix filled in, so you can see its range and plan how to divide it.
Typical prefix sizes
| Prefix | Typical use | /64 networks inside |
|---|---|---|
/32 | Allocation to an internet provider | 4,294,967,296 |
/48 | One site or business | 65,536 |
/56 | One home connection | 256 |
/64 | One network, such as a LAN or VLAN | 1 |
/127 | Link between two routers | — |
/128 | A single address | — |
Planning with nibbles
Each hex digit is 4 bits, so prefixes that are multiples of 4 (/48, /52, /56, /60, /64) end on a whole digit. Subnets planned on those boundaries are easier to read and to delegate in reverse DNS, whose names use one label per hex digit. The calculator shows that reverse DNS name too.
Related tools
For IPv4 blocks, see CIDR to IP range and the subnet mask cheat sheet.