CIDR Netmask Reverse Netmask IPs Class Cs Class Bs Class As
/32 255.255.255.255 0.0.0.0 1
/31 255.255.255.254 0.0.0.1 2
/30 255.255.255.252 0.0.0.3 4
/29 255.255.255.248 0.0.0.7 8
/28 255.255.255.240 0.0.0.15 16
/27 255.255.255.224 0.0.0.31 32
/26 255.255.255.192 0.0.0.63 64
/25 255.255.255.128 0.0.0.127 128
CIDR Netmask Reverse Netmask IPs
/24 255.255.255.0 0.0.0.255 256 1
/23 255.255.254.0 0.0.1.255 512 2
/22 255.255.252.0 0.0.3.255 1024 4
/21 255.255.248.0 0.0.7.255 2,048 8
/20 255.255.240.0 0.0.15.255 4,096 16
/19 255.255.224.0 0.0.31.255 8,192 32
/18 255.255.192.0 0.0.63.255 16,384 64
/17 255.255.128.0 0.0.127.255 32,768 128
CIDR Netmask Reverse Netmask IPs
/16 255.255.0.0 0.0.255.255 65,536 256 1
/15 255.254.0.0 0.1.255.255 131,072 512 2
/14 255.252.0.0 0.3.255.255 262,144 1,024 4
/13 255.248.0.0 0.7.255.255 524,288 2,048 8
/12 255.240.0.0 0.15.255.255 1,048,576 4,096 16
/11 255.224.0.0 0.31.255.255 2,097,152 8,192 32
/10 255.192.0.0 0.63.255.255 4,194,304 16,384 64
/9 255.128.0.0 0.127.255.255 8,388,608 32,768 128
CIDR Netmask Reverse Netmask IPs
/8 255.0.0.0 0.255.255.255 16,777,216 65,536 256 1
/7 254.0.0.0 1.255.255.255 33,554,432 131,072 512 2
/6 252.0.0.0 3.255.255.255 67,108,864 262,144 1,024 4
/5 248.0.0.0 7.255.255.255 134,217,728 524,288 2,048 8
/4 240.0.0.0 15.255.255.255 268,435,456 1,048,576 4,096 16
/3 224.0.0.0 31.255.255.255 536,870,912 2,097,152 8,192 32
/2 192.0.0.0 63.255.255.255 1,073,741,824 4,194,304 16,384 64
/1 128.0.0.0 127.255.255.255 2,147,483,648 8,388,608 32,768 128
CIDR Netmask Reverse Netmask IPs
/0 0.0.0.0 255.255.255.255 4,294,967,296 16,777,216 65,536 256
7 6 5 4 3 2 1 0
128 64 32 16 8 4 2 1 dec
80 40 20 10 8 4 2 1 hex