Here’s a complete IPv4 subnet cheat sheet formatted for easy reading, starting from /0 and ending at /32. It includes the CIDR notation, subnet mask, number of total addresses, and the number of usable addresses in each subnet.
Complete IPV4 Subnet
IPv4 Subnet Cheat Sheet
CIDR
Subnet Mask
Total Addresses
Host Range
About
/0
0.0.0.0
4,294,967,296
4,294,967,294
Entire IPv4 address space
/1
128.0.0.0
2,147,483,648
2,147,483,646
Half of the IPv4 address space
/2
192.0.0.0
1,073,741,824
1,073,741,822
Quarter of the IPv4 space
/3
224.0.0.0
536,870,912
536,870,910
/4
240.0.0.0
268,435,456
268,435,454
/5
248.0.0.0
134,217,728
134,217,726
/6
252.0.0.0
67,108,864
67,108,862
/7
254.0.0.0
33,554,432
33,554,430
/8
255.0.0.0
16,777,216
16,777,214
Class A network size ⬇️
/9
255.128.0.0
8,388,608
8,388,606
/10
255.192.0.0
4,194,304
4,194,302
/11
255.224.0.0
2,097,152
2,097,150
/12
255.240.0.0
1,048,576
1,048,574
/13
255.248.0.0
524,288
524,286
/14
255.252.0.0
262,144
262,142
/15
255.254.0.0
131,072
131,070
/16
255.255.0.0
65,536
65,534
Class B network size ⬇️
/17
255.255.128.0
32,768
32,766
/18
255.255.192.0
16,384
16,382
/19
255.255.224.0
8192
8,190
/20
255.255.240.0
4096
4,094
/21
255.255.248.0
2048
2,046
/22
255.255.252.0
1024
1,022
/23
255.255.254.0
512
510
/24
255.255.255.0
256
254
Class C network size ⬇️
/25
255.255.255.128
128
126
/26
255.255.255.192
64
62
/27
255.255.255.224
32
30
/28
255.255.255.240
16
14
/29
255.255.255.248
8
6
/30
255.255.255.252
4
2
Used for point-to-point links
/31
255.255.255.254
2
0*
Used for point-to-point links
/32
255.255.255.255
1
0
A single IP address
Notes:
*For /31 networks, there are technically no “usable” addresses for hosts, but these are used for point-to-point links where both addresses can be assigned. /31’s aren’t supported on all devices. When specifying the network address for a /31 you would usually use the other end points IP.
/32 networks are often used for loopback, or when a single IP address is defined, such as in routing.
Total Addresses: The total number of addresses in the subnet (including network and broadcastaddresses).
Host Range: The number of addresses available for hosts. This excludes the network address (first address) and the broadcast address (last address) for most subnets.
Public IPV4 Address Space
Address Range
Total Addresses
About
1.0.0.0/8 – 126.255.255.255/8
2,114,843,136
Read notes on reservations
128.0.0.0/8 – 191.255.255.255/8
1,073,741,824
Read notes on reservations
192.0.0.0/8 – 223.255.255.255/8
536,870,912
Read notes on reservations
Notes:
These massive IP ranges have several notable reservations within them, which you can read about blow. It’s important to note that due to these reservations not every single IP address in this space can be used publicly.
IPV4 Private Subnets
Address Range
CIDR
Total Addresses
Subnet Mask
About
10.0.0.0 – 10.255.255.255
/8
16,777,216
255.0.0.0
Formerly Class A
172.16.0.0 – 172.31.255.255
/12
1,048,576
255.240.0.0
Formerly Class A
192.168.0.0 – 192.168.255.255
/16
65,536
255.255.0.0
Formerly Class B
Notes:
10.0.0.0/8: Biggest private network block, used for very large networks (Class A).
172.16.0.0/12: Mid-sized private network block, often used in organizational settings (Class A).
192.168.0.0/16: The most common private network range for home and small office networks (Class B).
Reservations: All of these ranges can be used in private networks.
CGNAT Reserved Subnet
Address Range
CIDR
Total Addresses
Subnet Mask
About
100.64.0.0 – 100.127.255.255
/10
4,194,304
255.192.0.0
Reserved for CGNAT
Notes:
Address Range: 100.64.0.0 - 100.127.255.255 is reserved for CGNAT.
Uses: This range is reserved for use by ISPs for Carrier-Grade NAT, not usually for internal/private network use.
APIPA (Automatic Private Internet Protocol Addressing)
Address Range
CIDR
Total Addresses
Subnet Mask
About
169.254.0.0 – 169.254.255.255
/16
65,536
255.255.0.0
Used for Automatic Private IP Addressing (APIPA)
Notes:
169.254.0.0/16: This is the Link Local range, which is usually automatically assigned by an operating system when DHCP is unavailable and no static assignment exists, allowing devices to communicate on the local network without external configuration.
Loopback
Address Range
CIDR
Total Addresses
Subnet Mask
About
127.0.0.0 – 127.255.255.255
/8
16,777,216
255.0.0.0
Reserved for loopback (local host)
Notes:
127.0.0.0/8: Is the loopback range is used for communication within the local host.
127.0.0.1: The most common loopback address used to refer to the local machine. You’ve likely used this before when hosting a sever locally.
Multicast
Address Range
CIDR
Total Addresses
Subnet Mask
About
224.0.0.0 – 239.255.255.255
/4
268,435,456
240.0.0.0
Reserved for multicast traffic (RFC 5771)
Notes:
224.0.0.0/4: The multicast range is reserved for one-to-many communication, where data is sent to multiple recipients simultaneously (e.g., video streaming, network services, MDNS etc).
Class E (Experimental)
Address Range
CIDR
Total Addresses
Subnet Mask
About
240.0.0.0 – 255.255.255.254
/4
268,435,456
240.0.0.0
Reserved for future use (experimental)
Notes:
240.0.0.0/4: Class E addresses are reserved for experimental purposes and are not publicly routable on the internet.
Future Use: This range was designated for potential future use or research but is generally not used in production environments.
IPV4 Broadcast Address
Address Range
CIDR
Total Addresses
Subnet Mask
About
255.255.255.255
/32
1
255.255.255.255
Reserved for broadcast to all devices on a local network
Notes:
255.255.255.255: The broadcast address is used to send a message to all devices on a local network segment. It’s a single address that communicates with every host within the subnet.
Broadcast Use: Commonly used for sending DHCP discovery requests and other types of local network broadcasts.
0.0.0.0/8 (Current Network)
Addresses
CIDR
Total Addresses
Subnet Mask
About
0.0.0.0 – 0.255.255.255
/8
16,777,216
255.0.0.0
Reserved for special purposes
Notes:
0.0.0.0/8: This block is reserved for special purposes, like representing an unspecified address or default route.
Uses: DHCP (during the IP request process), server configuration (to bind to all interfaces).
