CIDR Subnet Mask Cheat Sheet

ByChase Smith Hours Updated on Categories Networking

We know it can be pain trying to remember which CIDR notation to use or what subnet mask to enter for a specific subnet. That’s why we created this awesome looking IPv4 CIDR cheat sheet for you to use.

Feel free to print it out and hang it up or share a link to it with your colleagues and peers.

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Free CIDR Subnet Mask Cheat Sheet

Free cheat sheet for IPv4 CIDR notation and subnet masks.

Click on the subnet mask chart to view the printable, searchable PDF version. Scroll down below for the CIDR subnet mask tables.

Related: Common Ports Cheat Sheet

IPv4 Subnets

An IPv4 subnet is a division of the IPv4 address space used to create smaller, interconnected networks within a larger network. It involves dividing the available IP addresses into subnetworks or subnets, each with its own unique range of addresses.

Subnetting allows for efficient allocation of IP addresses, improves network scalability and management, and enables logical segmentation of networks. Subnets are defined by combining an IP address with a subnet mask, which determines the network and host portions of the address.

CIDRSUBNET MASKADDRESSESWILDCARD
/00.0.0.04294967296255.255.255.255
/1128.0.0.02147483648127.255.255.255
/2192.0.0.0107374182463.255.255.255
/3224.0.0.053687091231.255.255.255
/4240.0.0.026843545615.255.255.255
/5248.0.0.01342177287.255.255.255
/6252.0.0.0671088643.255.255.255
/7254.0.0.0335544321.255.255.255
/8255.0.0.0167772160.255.255.255
/9255.128.0.083886080.127.255.255
/10255.192.0.041943040.63.255.255
/11255.224.0.020971520.31.255.255
/12255.240.0.010485760.15.255.255
/13255.248.0.05242880.7.255.255
/14255.252.0.02621440.3.255.255
/15255.254.0.01310720.1.255.255
/16255.255.0.0655360.0.255.255
/17255.255.128.0327680.0.127.255
/18255.255.192.0163840.0.63.255
/19255.255.224.081920.0.31.255
/20255.255.240.040960.0.15.255
/21255.255.248.020480.0.7.255
/22255.255.252.010240.0.3.255
/23255.255.254.05120.0.1.255
/24255.255.255.02560.0.0.255
/25255.255.255.1281280.0.0.127
/26255.255.255.192640.0.0.63
/27255.255.255.224320.0.0.31
/28255.255.255.240160.0.0.15
/29255.255.255.24880.0.0.7
/30255.255.255.25240.0.0.3
/31255.255.255.25420.0.0.1
/32255.255.255.25510.0.0.0

See also RFC1878

Classful Ranges

A classful range refers to a predefined range of IP addresses based on the original classful addressing scheme. The classful addressing scheme divides the IPv4 address space into five classes: A, B, C, D, and E. Each class has a specific range of IP addresses and a default mask associated with it. Classful ranges are characterized by fixed network and host portions based on the class with Class A having the largest network portion and Class C having the smallest.

Classful addressing has been largely replaced by classless inter-domain routing (CIDR), which allows for more flexible allocation of IP addresses by using variable-length subnet masks (VLSM).

Class NameIP Range
Class A0.0.0.0 – 127.255.255.255
Class B128.0.0.0 – 191.255.255.255
Class C192.0.0.0 – 223.255.255.255
Class D224.0.0.0 – 239.255.255.255
Class E240.0.0.0 – 254.255.255.254

Reserved Ranges

Reserved ranges are specific blocks of IP addresses that are designated for special purposes and are not available for general allocation or public use. These reserved ranges include private IP address ranges, loopback addresses, link-local addresses, and multicast addresses.

Range NameIP Range
RFC 191810.0.0.0 – 10.255.255.255
Localhost127.0.0.0 – 127.255.255.255
APIPA/BONJOUR169.254.0.0 – 169.254.255.255
RFC 1918172.16.0.0 – 172.31.255.255
RFC 1918192.168.0.0 – 192.168.255.255

See also RFC1918

Bogon IPv4 Addresses and Ranges

Bogon addresses are IP addresses or address blocks that are invalid, unallocated, or not globally routable. Bogon addresses include IP addresses that should not appear on the internet and are commonly used in spoofing or malicious activities. These addresses may include reserved IP ranges, multicast addresses, or addresses that have not been assigned by the Internet Assigned Numbers Authority (IANA) or regional Internet registries.

NetblockDescription
0.0.0.0/8“This” network
10.0.0.0/8Private-use networks
100.64.0.0/10Carrier-grade NAT
127.0.0.0/8Loopback
127.0.53.53Name collision occurrence
169.254.0.0/16Link local
172.16.0.0/12Private-use networks
192.0.0.0/24IETF protocol assignments
192.0.2.0/24TEST-NET-1
192.168.0.0/16Private-use networks
198.18.0.0/15Network interconnect device benchmark testing
198.51.100.0/24TEST-NET-2
203.0.113.0/24TEST-NET-3
224.0.0.0/4Multicast
240.0.0.0/4Reserved for future use