CIDR - Subnet Mask Table

Conversion table for CIDR notation

CIDR length Subnet Mask Inverse Mask Classfull Subnets Usable IP Addresses
/1 128.0.0.0 127.255.255.255 128 2,147,483,646
/2 192.0.0.0 63.255.255.255 64 1073741822
/3 224.0.0.0 31.255.255.255 32 536870910
/4 240.0.0.0 15.255.255.255 16 268435454
/5 248.0.0.0 7.255.255.255 8 134.217.726
/6 252.0.0.0 3.255.255.255 4 67108862
/7 254.0.0.0 1.255.255.255 2 33554430
/8 255.0.0.0 0.255.255.255 1 16777214
/9 255.128.0.0 0.127.255.255 128 8388606
/10 255.192.0.0 0.63.255.255 64 4194302
/11 255.224.0.0 0.31.255.255 32 2097150
/12 225.240.0.0 0.15.255.255 16 1048574
/13 255.248.0.0 0.7.255.255 8 524286
/14 255.252.0.0 0.3.255.255 4 262142
/15 255.254.0.0 0.1.255.255 2 131070
/16 255.255.0.0 0.0.255.255 1 65534
/17 255.255.128.0 0.0.127.255 128 32766
/18 255.255.192.0 0.0.63.255 64 16382
/19 255.255.224.0 0.0.31.255 32 8190
/20 255.255.240.0 0.0.15.255 16 4094
/21 255.255.248.0 0.0.7.255 8 2046
/22 255.255.252.0 0.0.3.255 4 1022
/23 255.255.254.0 0.0.1.255 2 510
/24 255.255.255.0 0.0.0.255 1 254
/25 255.255.255.128 0.0.0.127 128 126
/26 255.255.255.192 0.0.0.63 64 62
/27 255.255.255.224 0.0.0.31 32 30
/28 255.255.255.240 0.0.0.15 16 14
/29 255.255.255.248 0.0.0.7 8 6
/30 255.255.255.252 0.0.0.3 4 2
/31 255.255.255.254 0.0.0.1 1 0
/31 255.255.255.255 0.0.0.0 1 1