| CIDR prefix bit length | Dotted Decimal | Binary | Hex | # of usable IP's | Class |
| /0 | 0.0.0.0 | 0000 0000 0000 0000 0000 0000 0000 0000 | 00-00-00-00 | (get real!) | |
| /1 | 128.0.0.0 | 1000 0000 0000 0000 0000 0000 0000 0000 | 80-00-00-00 | 2,147,483,648 | 128 A's |
| /2 | 192.0.0.0 | 1100 0000 0000 0000 0000 0000 0000 0000 | C0-00-00-00 | 1,073,741,824 | 64 A's |
| /3 | 224.0.0.0 | 1110 0000 0000 0000 0000 0000 0000 0000 | E0-00-00-00 | 536,870,912 | 32 A's |
| /4 | 240.0.0.0 | 1111 0000 0000 0000 0000 0000 0000 0000 | F0-00-00-00 | 268,435,456 | 16 A's |
| /5 | 248.0.0.0 | 1111 1000 0000 0000 0000 0000 0000 0000 | F8-00-00-00 | 134,217,728 | 8 A's |
| /6 | 252.0.0.0 | 1111 1100 0000 0000 0000 0000 0000 0000 | FC-00-00-00 | 67,108,864 | 4 A's |
| /7 | 254.0.0.0 | 1111 1110 0000 0000 0000 0000 0000 0000 | FE-00-00-00 | 33,554,432 | 2 A's |
| /8 | 255.0.0.0 | 1111 1111 0000 0000 0000 0000 0000 0000 | FF-00-00-00 | 16,777,216 | 1 A or 256 B's |
| /9 | 255.128.0.0 | 1111 1111 1000 0000 0000 0000 0000 0000 | FF-80-00-00 | 8,388,608 | 128 B's |
| /10 | 255.192.0.0 | 1111 1111 1100 0000 0000 0000 0000 0000 | FF-C0-00-00 | 4,194,304 | 64 B's |
| /11 | 255.224.0.0 | 1111 1111 1110 0000 0000 0000 0000 0000 | FF-E0-00-00 | 2,097,125 | 32 B's |
| /12 | 255.240.0.0 | 1111 1111 1111 0000 0000 0000 0000 0000 | FF-F0-00-00 | 1,048,576 | 16 B's |
| /13 | 255.248.0.0 | 1111 1111 1111 1000 0000 0000 0000 0000 | FF-F8-00-00 | 524,288 | 8 B's |
| /14 | 255.252.0.0 | 1111 1111 1111 1100 0000 0000 0000 0000 | FF-FC-00-00 | 262,144 | 4 B's |
| /15 | 255.254.0.0 | 1111 1111 1111 1110 0000 0000 0000 0000 | FF-FE-00-00 | 131,072 | 2 B's |
| /16 | 255.255.0.0 | 1111 1111 1111 1111 0000 0000 0000 0000 | FF-FF-00-00 | 65,536 | 1 B or 256 C's |
| /17 | 255.255.128.0 | 1111 1111 1111 1111 1000 0000 0000 0000 | FF-FF-80-00 | 32,768 | 128 C's |
| /18 | 255.255.192.0 | 1111 1111 1111 1111 1100 0000 0000 0000 | FF-FF-C0-00 | 16,384 | 64 C's |
| /19 | 255.255.224.0 | 1111 1111 1111 1111 1110 0000 0000 0000 | FF-FF-E0-00 | 8,192 | 32 C's |
| /20 | 255.255.240.0 | 1111 1111 1111 1111 1111 0000 0000 0000 | FF-FF-F0-00 | 4,096 | 16 C's |
| /21 | 255.255.248.0 | 1111 1111 1111 1111 1111 1000 0000 0000 | FF-FF-F8-00 | 2,048 | 8 C's |
| /22 | 255.255.252.0 | 1111 1111 1111 1111 1111 1100 0000 0000 | FF-FF-FC-00 | 1,024 | 4 C's |
| /23 | 255.255.254.0 | 1111 1111 1111 1111 1111 1110 0000 0000 | FF-FF-FE-00 | 512 | 2 C's |
| /24 | 255.255.255.0 | 1111 1111 1111 1111 1111 1111 0000 0000 | FF-FF-FF-00 | 256 | 1 C |
| /25 | 255.255.255.128 | 1111 1111 1111 1111 1111 1111 1000 0000 | FF-FF-FF-80 | 128 | 1/2 C |
| /26 | 255.255.255.192 | 1111 1111 1111 1111 1111 1111 1100 0000 | FF-FF-FF-C0 | 64 | 1/4 C |
| /27 | 255.255.255.224 | 1111 1111 1111 1111 1111 1111 1110 0000 | FF-FF-FF-E0 | 32 | 1/8 C |
| /28 | 255.255.255.240 | 1111 1111 1111 1111 1111 1111 1111 0000 | FF-FF-FF-F0 | 16 | 1/16 C |
| /29 | 255.255.255.248 | 1111 1111 1111 1111 1111 1111 1111 1000 | FF-FF-FF-F8 | 8 | 1/32 C |
| /30 | 255.255.255.252 | 1111 1111 1111 1111 1111 1111 1111 1100 | FF-FF-FF-FC | 4 | 1/64 C |
| /31 | 255.255.255.254 | 1111 1111 1111 1111 1111 1111 1111 1110 | FF-FF-FF-FE | 2 | 1/128 C |