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 |