IP Subnetting Cheat Sheet

Contents
CIDR Prefix Table
IP Class Address Ranges
Reserved Private IP Address Ranges
Leading Bit Patterns by IP Class

CIDR Prefix Table

PrefixSubnet MaskHostsWildcard Mask
/30255.255.255.25220.0.0.3
/29255.255.255.24860.0.0.7
/28255.255.255.240140.0.0.15
/27255.255.255.224300.0.0.31
/26255.255.255.192620.0.0.63
/25255.255.255.128120.0.0.127
/24255.255.255.02540.0.0.255
/23255.255.254.05100.0.1.255
/22255.255.252.01,0220.0.3.255
/21255.255.248.02,0460.0.7.255
/20255.255.240.04,0940.0.15.255
/19255.255.224.08,1900.0.31.255
/18255.255.192.016,3820.0.63.255
/17255.255.128.032,7660.0.127.255
/16255.255.0.065,5340.0.255.255
/15255.254.0.0131,0700.1.255.255
/14255.252.0.0262,1420.3.255.255
/13255.248.0.0524,2860.7.255.255
/12255.240.0.01,048,5740.15.255.255
/11255.224.0.02,097,1500.31.255.255
/10255.192.0.04,194,3020.63.255.255
/9255.128.0.08,388,6060.127.255.255
/8255.0.0.016,777,2140.255.255.255

IP Class Address Ranges

Class A1.x.x.x to 126.x.x.x
Class B128.0.x.x to 191.255.x.x
Class C192.0.0.x to 223.255.255.x
Class D224.0.0.0 to 239.255.255.255 (Multicast)
Class E240.0.0.0 to 255.255.255.255 (Reserved)
Loopback127.x.x.x

Reserved Private IP Address Space (RFC 1918)

Class A10.x.x.x
Class B172.16.x.x - 172.31.x.x
Class C192.168.x.x

Leading Bit Patterns by IP Class

Class A0
Class B10
Class C110
Class D1110
Class E1111