IPv6 subnet splitter
Split an IPv6 prefix into equal subnets, like a /48 into /64 LANs or a /32 into /48 sites. Choose a new prefix length or how many subnets you need.
Subnets
Example: type your own block above.
| # | Subnet | First | Last |
|---|---|---|---|
| 1 | 2001:db8:abcd::/64 | 2001:db8:abcd:: | 2001:db8:abcd:0:ffff:ffff:ffff:ffff |
| 2 | 2001:db8:abcd:1::/64 | 2001:db8:abcd:1:: | 2001:db8:abcd:1:ffff:ffff:ffff:ffff |
| 3 | 2001:db8:abcd:2::/64 | 2001:db8:abcd:2:: | 2001:db8:abcd:2:ffff:ffff:ffff:ffff |
| 4 | 2001:db8:abcd:3::/64 | 2001:db8:abcd:3:: | 2001:db8:abcd:3:ffff:ffff:ffff:ffff |
| 5 | 2001:db8:abcd:4::/64 | 2001:db8:abcd:4:: | 2001:db8:abcd:4:ffff:ffff:ffff:ffff |
| 6 | 2001:db8:abcd:5::/64 | 2001:db8:abcd:5:: | 2001:db8:abcd:5:ffff:ffff:ffff:ffff |
| 7 | 2001:db8:abcd:6::/64 | 2001:db8:abcd:6:: | 2001:db8:abcd:6:ffff:ffff:ffff:ffff |
| 8 | 2001:db8:abcd:7::/64 | 2001:db8:abcd:7:: | 2001:db8:abcd:7:ffff:ffff:ffff:ffff |
| 9 | 2001:db8:abcd:8::/64 | 2001:db8:abcd:8:: | 2001:db8:abcd:8:ffff:ffff:ffff:ffff |
| 10 | 2001:db8:abcd:9::/64 | 2001:db8:abcd:9:: | 2001:db8:abcd:9:ffff:ffff:ffff:ffff |
| 11 | 2001:db8:abcd:a::/64 | 2001:db8:abcd:a:: | 2001:db8:abcd:a:ffff:ffff:ffff:ffff |
| 12 | 2001:db8:abcd:b::/64 | 2001:db8:abcd:b:: | 2001:db8:abcd:b:ffff:ffff:ffff:ffff |
| 13 | 2001:db8:abcd:c::/64 | 2001:db8:abcd:c:: | 2001:db8:abcd:c:ffff:ffff:ffff:ffff |
| 14 | 2001:db8:abcd:d::/64 | 2001:db8:abcd:d:: | 2001:db8:abcd:d:ffff:ffff:ffff:ffff |
| 15 | 2001:db8:abcd:e::/64 | 2001:db8:abcd:e:: | 2001:db8:abcd:e:ffff:ffff:ffff:ffff |
| 16 | 2001:db8:abcd:f::/64 | 2001:db8:abcd:f:: | 2001:db8:abcd:f:ffff:ffff:ffff:ffff |
- #
- 1
- Subnet
- 2001:db8:abcd::/64
- First
- 2001:db8:abcd::
- Last
- 2001:db8:abcd:0:ffff:ffff:ffff:ffff
- #
- 2
- Subnet
- 2001:db8:abcd:1::/64
- First
- 2001:db8:abcd:1::
- Last
- 2001:db8:abcd:1:ffff:ffff:ffff:ffff
- #
- 3
- Subnet
- 2001:db8:abcd:2::/64
- First
- 2001:db8:abcd:2::
- Last
- 2001:db8:abcd:2:ffff:ffff:ffff:ffff
- #
- 4
- Subnet
- 2001:db8:abcd:3::/64
- First
- 2001:db8:abcd:3::
- Last
- 2001:db8:abcd:3:ffff:ffff:ffff:ffff
- #
- 5
- Subnet
- 2001:db8:abcd:4::/64
- First
- 2001:db8:abcd:4::
- Last
- 2001:db8:abcd:4:ffff:ffff:ffff:ffff
- #
- 6
- Subnet
- 2001:db8:abcd:5::/64
- First
- 2001:db8:abcd:5::
- Last
- 2001:db8:abcd:5:ffff:ffff:ffff:ffff
- #
- 7
- Subnet
- 2001:db8:abcd:6::/64
- First
- 2001:db8:abcd:6::
- Last
- 2001:db8:abcd:6:ffff:ffff:ffff:ffff
- #
- 8
- Subnet
- 2001:db8:abcd:7::/64
- First
- 2001:db8:abcd:7::
- Last
- 2001:db8:abcd:7:ffff:ffff:ffff:ffff
- #
- 9
- Subnet
- 2001:db8:abcd:8::/64
- First
- 2001:db8:abcd:8::
- Last
- 2001:db8:abcd:8:ffff:ffff:ffff:ffff
- #
- 10
- Subnet
- 2001:db8:abcd:9::/64
- First
- 2001:db8:abcd:9::
- Last
- 2001:db8:abcd:9:ffff:ffff:ffff:ffff
- #
- 11
- Subnet
- 2001:db8:abcd:a::/64
- First
- 2001:db8:abcd:a::
- Last
- 2001:db8:abcd:a:ffff:ffff:ffff:ffff
- #
- 12
- Subnet
- 2001:db8:abcd:b::/64
- First
- 2001:db8:abcd:b::
- Last
- 2001:db8:abcd:b:ffff:ffff:ffff:ffff
- #
- 13
- Subnet
- 2001:db8:abcd:c::/64
- First
- 2001:db8:abcd:c::
- Last
- 2001:db8:abcd:c:ffff:ffff:ffff:ffff
- #
- 14
- Subnet
- 2001:db8:abcd:d::/64
- First
- 2001:db8:abcd:d::
- Last
- 2001:db8:abcd:d:ffff:ffff:ffff:ffff
- #
- 15
- Subnet
- 2001:db8:abcd:e::/64
- First
- 2001:db8:abcd:e::
- Last
- 2001:db8:abcd:e:ffff:ffff:ffff:ffff
- #
- 16
- Subnet
- 2001:db8:abcd:f::/64
- First
- 2001:db8:abcd:f::
- Last
- 2001:db8:abcd:f:ffff:ffff:ffff:ffff
Showing the first 16 of 65,536 subnets.
How it works
Splitting a block means cutting it into equal, smaller blocks. Each extra prefix bit doubles the number of subnets and halves their size. For example, 2001:db8:abcd::/48 splits into 256 /56s or 65,536 /64s.
Asking for a number of subnets rounds up to the next power of two, because subnets only come in those sizes: 5 subnets of a /24 become 8 /27s. Asking for hosts per subnet picks the smallest block that fits. On IPv4, that includes the network and broadcast addresses, so 50 hosts need a /26 (62 usable).
On IPv6, each LAN should be a /64, because SLAAC (how devices give themselves an address) needs 64 host bits. A site usually gets a /48 (65,536 LANs) and a home often a /56 (256 LANs). Prefixes that are a multiple of 4 keep subnet numbers on whole hex digits, which makes them easier to read.
When subnets need different sizes, use the VLSM calculator. To check one subnet in detail, use the subnet calculator.