IPv6 subnet matrix table

This is a table of the IP block space available in various IPv6 prefixes.

The IPv6 Subnet Matrix Table

2001:0DB8:0400:000e:0000:0000:0000:402b
XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX
      ||| |||| |||| |||| |||| |||| ||||
      ||| |||| |||| |||| |||| |||| |||128
      ||| |||| |||| |||| |||| |||| ||124
      ||| |||| |||| |||| |||| |||| |120
      ||| |||| |||| |||| |||| |||| 116
      ||| |||| |||| |||| |||| |||112
      ||| |||| |||| |||| |||| ||108
      ||| |||| |||| |||| |||| |104
      ||| |||| |||| |||| |||| 100
      ||| |||| |||| |||| |||96
      ||| |||| |||| |||| ||92
      ||| |||| |||| |||| |88
      ||| |||| |||| |||| 84
      ||| |||| |||| |||80
      ||| |||| |||| ||76
      ||| |||| |||| |72
      ||| |||| |||| 68
      ||| |||| |||64
      ||| |||| ||60
      ||| |||| |56
      ||| |||| 52
      ||| |||48
      ||| ||44
      ||| |40
      ||| 36
      ||32
      |28
      24

Examples

If you are granted a /64 prefix like 2001:0DB8:0400:000e::/64 then what's left after /64 in the table above is XXXX:XXXX:XXXX:XXXX. You have XXXX:XXXX:XXXX:XXXX (0000:0000:0000:0000 - FFFF:FFFF:FFFF:FFFF) at your disposal.

If you are handed a /124 prefix like 2001:0DB8:0400:000e:0000:0000:0000:402/124 then you are only left with X (0-F). Two are typically used to create the link, which leaves 14 IP's available to be used at your discretion.

The actual number of IPv6 in various subnet sizes

Prefix	Number of IPv6 IPs	Space
127	2	none
124	16	x
120	256	xx
64	18,446,744,073,709,551,616	xxxx:xxxx:xxxx:xxxx
48	1,208,925,819,614,629,174,706,176	xxxx:xxxx:xxxx:xxxx:xxxx
32	79,228,162,514,264,337,593,543,950,336	xxxx:xxxx:xxxx:xxxx:xxxx:xxxx

Requirements

You typically want/need a /64 for your home network. This is because /64 is the required size to use for autoconfiguraiton using radvd etc.. Smaller than /64 prefixes simply don't work with IPv6 autoconfiguration.

A /112 prefix (XXXX) or /96 (XXXX:XXXX) are nice sizes to allocate to each server in serverfarms etc.