IP Subnet Cheat Sheet

If you work with networking or IT, you’re probably familiar with IP subnetting. Subnetting is the process of dividing a larger network into smaller subnetworks, or subnets. This cheat sheet provides the subnet masks and number of subnets/hosts per subnet for common prefix lengths in IPv4 and IPv6.

IPv4

Prefix Length Subnet Mask Number of Subnets Number of Hosts per Subnet
/8 255.0.0.0 128 16,777,214
/9 255.128.0.0 256 8,388,606
/10 255.192.0.0 512 4,194,302
/11 255.224.0.0 1,024 2,097,150
/12 255.240.0.0 2,048 1,048,574
/13 255.248.0.0 4,096 524,286
/14 255.252.0.0 8,192 262,142
/15 255.254.0.0 16,384 131,070
/16 255.255.0.0 32,768 65,534
/17 255.255.128.0

IPv6

Prefix Length Subnet Mask Number of Subnets Number of Hosts per Subnet
/32 ffff:ffff:: 1 4,294,967,294,967,296
/48 ffff:ffff:ffff:: 65,536 1.2089 x 10^24
/56 ffff:ffff:ff00:: 256 1.4615 x 10^16
/64 ffff:ffff:ffff:ffff:: 1 18,446,744,073,709,551,616
/96 ffff:ffff:ffff:ffff:ffff:ffff:: 65,536 1.2089 x 10^24
/112 ffff:ffff:ffff:ffff:ffff:ffff:ff00:: 256 1.4615 x 10^16
/128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 1 1