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Ths is an Internet Protocol (IPv4) Subnet Chart. You can use this to quickly look up how your might need to subnet your network. At the bottom there is a quick how-to on calculating subnets.

For more information on subnetting, see RFC 1817 and RFC 1812.

Class address ranges:

  • Class A = 1.0.0.0 to 126.0.0.0
  • Class B = 128.0.0.0 to 191.255.0.0
  • Class C = 192.0.1.0 to 223.255.255.0

 

Reserved address ranges for private (non-routed) use (see RFC 1918):

  • 10.0.0.0 -> 10.255.255.255
  • 172.16.0.0 -> 172.31.255.255
  • 192.168.0.0 -> 192.168.255.255

 

Other reserved addresses:

  • 127.0.0.0 is reserved for loopback and IPC on the local host
  • 224.0.0.0 -> 239.255.255.255 is reserved for multicast addresses

 

Chart notes:

  • Number of Subnets – “( )” Refers to the number of effective subnets, since the use of subnet numbers of all 0s or all 1s is highly frowned upon and RFC non-compliant.
  • Number of Hosts – Refers to the number of effective hosts, excluding the network and broadcast address.

 

 

Class A

Network BitsSubnet MaskNumber of SubnetsNumber of Hosts
/8255.0.0.0016777214
/9255.128.0.02 (0)8388606
/10255.192.0.04 (2)4194302
/11255.224.0.08 (6)2097150
/12255.240.0.016 (14)1048574
/13255.248.0.032 (30)524286
/14255.252.0.064 (62)262142
/15255.254.0.0128 (126)131070
/16255.255.0.0256 (254)65534
/17255.255.128.0512 (510)32766
/18255.255.192.01024 (1022)16382
/19255.255.224.02048 (2046)8190
/20255.255.240.04096 (4094)4094
/21255.255.248.08192 (8190)2046
/22255.255.252.016384 (16382)1022
/23255.255.254.032768 (32766)510
/24255.255.255.065536 (65534)254
/25255.255.255.128131072 (131070)126
/26255.255.255.192262144 (262142)62
/27255.255.255.224524288 (524286)30
/28255.255.255.2401048576 (1048574)14
/29255.255.255.2482097152 (2097150)6
/30255.255.255.2524194304 (4194302)2

 

Class B

Network BitsSubnet MaskNumber of SubnetsNumber of Hosts
/16255.255.0.0065534
/17255.255.128.02 (0)32766
/18255.255.192.04 (2)16382
/19255.255.224.08 (6)8190
/20255.255.240.016 (14)4094
/21255.255.248.032 (30)2046
/22255.255.252.064 (62)1022
/23255.255.254.0128 (126)510
/24255.255.255.0256 (254)254
/25255.255.255.128512 (510)126
/26255.255.255.1921024 (1022)62
/27255.255.255.2242048 (2046)30
/28255.255.255.2404096 (4094)14
/29255.255.255.2488192 (8190)6
/30255.255.255.25216384 (16382)2

 

Class C

Network BitsSubnet MaskNumber of SubnetsNumber of Hosts
/24255.255.255.00254
/25255.255.255.1282 (0)126
/26255.255.255.1924 (2)62
/27255.255.255.2248 (6)30
/28255.255.255.24016 (14)14
/29255.255.255.24832 (30)6
/30255.255.255.25264 (62)2

Supernetting (CIDR) Chart

  • CIDR – Classless Inter-Domain Routing.
  • Note: The Number of Class C networks must be contiguous.
    For example, 192.169.1.0/22 represents the following block of addresses:
    192.169.1.0, 192.169.2.0, 192.169.3.0 and 192.169.4.0.

Class C

CIDR BlockSupernet MaskNumber of Class C AddressesNumber of Hosts
/14255.252.0.01024262144
/15255.254.0.0512131072
/16255.255.0.025665536
/17255.255.128.012832768
/18255.255.192.06416384
/19255.255.224.0328192
/20255.255.240.0164096
/21255.255.248.082048
/22255.255.252.041024
/23255.255.254.02512