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CIDR Conversion Table

Conversion table for CIDR notation.

CIDR Conversion Table

CIDR prefix length

Dotted Decimal Netmask

Hexidecimal Netmask

Inverse Netmask

Binary

Number of Classfull Networks

Number of Usable IPs


/1 128.0.0.0 80 00 00 00 127.255.255.255 1000 0000 0000 0000 0000 0000 0000 0000 128 As 2,147,483,646
/2 192.0.0.0 C0 00 00 00 63.255.255.255 1100 0000 0000 0000 0000 0000 0000 0000 64 As 1,073,741,822
/3 224.0.0.0 E0 00 00 00 31.255.255.255 1110 0000 0000 0000 0000 0000 0000 0000 32 As 536,870,910
/4 240.0.0.0 F0 00 00 00 15.255.255.255 1111 0000 0000 0000 0000 0000 0000 0000 16 As 268,435,454
/5 248.0.0.0 F8 00 00 00 7.255.255.255 1111 1000 0000 0000 0000 0000 0000 0000 8 As 134,217,726
/6 252.0.0.0 FC 00 00 00 3.255.255.255 1111 1100 0000 0000 0000 0000 0000 0000 4 As 67,108,862
/7 254.0.0.0 FE 00 00 00 1.255.255.255 1111 1110 0000 0000 0000 0000 0000 0000 2 As 33,554,430
/8 255.0.0.0 FF 00 00 00 0.255.255.255 1111 1111 0000 0000 0000 0000 0000 0000 1 A or 256 Bs 16,777,214

/9 255.128.0.0 FF 80 00 00 0.127.255.255 1111 1111 1000 0000 0000 0000 0000 0000 128 Bs 8,388,606
/10 255.192.0.0 FF C0 00 00 0.63.255.255 1111 1111 1100 0000 0000 0000 0000 0000 64 Bs 4,194,302
/11 255.224.0.0 FF E0 00 00 0.31.255.255 1111 1111 1110 0000 0000 0000 0000 0000 32 Bs 2,097,150
/12 255.240.0.0 FF F0 00 00 0.15.255.255 1111 1111 1111 0000 0000 0000 0000 0000 16 Bs 1,048,574
/13 255.248.0.0 FF F8 00 00 0.7.255.255 1111 1111 1111 1000 0000 0000 0000 0000 8 Bs 524,286
/14 255.252.0.0 FF FC 00 00 0.3.255.255 1111 1111 1111 1100 0000 0000 0000 0000 4 Bs 262,142
/15 255.254.0.0 FF FE 00 00 0.1.255.255 1111 1111 1111 1110 0000 0000 0000 0000 2 Bs 131,070
/16 255.255.0.0 FF FF 00 00 0.0.255.255 1111 1111 1111 1111 0000 0000 0000 0000 1 B or 256 Cs 65,534

/17 255.255.128.0 FF FF 80 00 0.0.127.255 1111 1111 1111 1111 1000 0000 0000 0000 128 Cs 32,766
/18 255.255.192.0 FF FF C0 00 0.0.63.255 1111 1111 1111 1111 1100 0000 0000 0000 64 Cs 16,382
/19 255.255.224.0 FF FF E0 00 0.0.31.255 1111 1111 1111 1111 1110 0000 0000 0000 32 Cs 8,190
/20 255.255.240.0 FF FF F0 00 0.0.15.255 1111 1111 1111 1111 1111 0000 0000 0000 16 Cs 4,094
/21 255.255.248.0 FF FF F8 00 0.0.7.255 1111 1111 1111 1111 1111 1000 0000 0000 8 Cs 2,046
/22 255.255.252.0 FF FF FC 00 0.0.3.255 1111 1111 1111 1111 1111 1100 0000 0000 4 Cs 1,022
/23 255.255.254.0 FF FF FE 00 0.0.1.255 1111 1111 1111 1111 1111 1110 0000 0000 2 Cs 510
/24 255.255.255.0 FF FF FF 00 0.0.0.255 1111 1111 1111 1111 1111 1111 0000 0000 1 C 254

/25 255.255.255.128 FF FF FF 80 0.0.0.127 1111 1111 1111 1111 1111 1111 1000 0000 1/2 C 126
/26 255.255.255.192 FF FF FF C0 0.0.0.63 1111 1111 1111 1111 1111 1111 1100 0000 1/4 C 62
/27 255.255.255.224 FF FF FF E0 0.0.0.31 1111 1111 1111 1111 1111 1111 1110 0000 1/8 C 30
/28 255.255.255.240 FF FF FF F0 0.0.0.15 1111 1111 1111 1111 1111 1111 1111 0000 1/16 C 14
/29 255.255.255.248 FF FF FF F8 0.0.0.7 1111 1111 1111 1111 1111 1111 1111 1000 1/32 C 6
/30 255.255.255.252 FF FF FF FC 0.0.0.3 1111 1111 1111 1111 1111 1111 1111 1100 1/64 C 2
/31 255.255.255.254 FF FF FF FE 0.0.0.1 1111 1111 1111 1111 1111 1111 1111 1110 1/128 C 0
/32 255.255.255.255 FF FF FF FF 0.0.0.0 1111 1111 1111 1111 1111 1111 1111 1111 1/256 C 1
 
Reserved Network Numbers
Class Start End Number of IPs Comment

  A   10.0.0.0   10.255.255.255   16,777,216   A single Class A network number
  B   172.16.0.0   172.31.255.255 1,048,544   16 contiguous Class B network numbers
  C   192.168.0.0     192.168.255.255   65,534   256 contiguous Class C network numbers  

CIDR Conversion Table originally sourced from Belchfire.net




Keywords: CIDR subnet mask conversion ip   Doc ID: 3493
Owner: Jeff R.Group: Network Services
Created: 2005-02-21 19:00 CDTUpdated: 2013-01-24 11:06 CDT
Sites: Network Services, Systems & Network Control Center