IPv4 Subnet Mask Cheat Sheet CIDR Subnet Mask Total IPs Usable IPs /32 255.255.255.255 1 1 /31 255.255.255.254 2 2* /30 255.255.255.252 4 2 /29 255.255.255.248 8 6 /28 255.255.255.240 16 14 /27 255.255.255.224 32 30 /26 255.255.255.192 64 62 /25 255.255.255.128 128 126 /24 255.255.255.0 256 254 /23 255.255.254.0 512 510 /22 255.255.252.0 1024 1022 /21 255.255.248.0 2048 2046 /20 255.255.240.0 4096 4094 /19 255.255.224.0 8192 8190 /18 255.255.192.0 16,384 16,382 /17 255.255.128.0 32,768 32,766 /16 255.255.0.0 65,536 65,534 /15 255.254.0.0 131,072 131,070 /14 255.252.0.0 262,144 262,142 /13 255.248.0.0 524,288 524,286 /12 255.240.0.0 1,048,576 1,048,574 /11 255.224.0.0 2,097,152 2,097,150 /10 255.192.0.0 4,194,304 4,194,302 /9 255.128.0.0 8,388,608 8,388,606 /8 255.0.0.0 16,777,216 16,777,214 /7 254.0.0.0 33,554,432 33,554,430 /6 252.0.0.0 67,108,864 67,108,862 /5 248.0.0.0 134,217,728 134,217,726 /4 240.0.0.0 268,435,456 268,435,454 /3 224.0.0.0 536,870,912 536,870,910 /2 192.0.0.0 1,073,741,824 1,073,741,822 /1 128.0.0.0 2,147,483,648 2,147,483,646