Subnetmask in HEX

Overview of common subnets and masks Mask Hosts  Usable Netmask          Hex Mask /30  4      2      255.255.255.252  fffffffc  this is 1/64 of a Class C net /29  8      6      255.255.255.248  fffffff8  this is 1/32 of a Class C net /28  16     14     255.255.255.240  fffffff0  this is 1/16 of a Class C net /27  32     30     255.255.255.224  ffffffe0  this is 1/8 of a Class C net /26  64     62     255.255.255.192  ffffffc0  this is 1/4 of a Class C net /24  256    254    255.255.255.0    ffffff00  this is a Class C net /23  512    510    255.255.254.0    fffffe00  these are 2 Class C net /22  1024   1022   255.255.252.0    fffffc00  these are 4 Class C net /21  2048   2046   255.255.248.0    fffff800  these are 8 Class C net /20  4096   4094   255.255.240.0    fffff000  these are 16 Class C net /19  8192   8190   255.255.224.0    ffffe000  these are 32 Class C net /18  16384  16382  255.255.192.0    ffffc000  these are 64 Class C net /17  32768  32766  255.255.128.0    ffff8000  these are 128 Class C net /16  65536  65534  255.255.0.0      ffff0000  these are 256 Class C net = Class B net