Subnetting is the process of dividing one network into smaller networks. Collectively, the smaller networks are referred to as subnetworks (or subnets), and the singular subdivision is a subnetwork (more commonly referred to as a subnet). Every single computer that is connected to a subnet shares an identical portion of the IP address. This shared information is known as a routing prefix, and in IPV4 (Internet Protocol Version 4), the routing prefix is called a subnet mask. The subnet mask is a "quad-dotted decimal representation".
This IPv4 Subnet Chart can assist you in looking up how a network is broken up into subnets.
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:
- 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 Bits | Subnet Mask | Number of Subnets | Number of Hosts |
/8 | 255.0.0.0 | 0 | 16777214 |
/9 | 255.128.0.0 | 2 (0) | 8388606 |
/10 | 255.192.0.0 | 4 (2) | 4194302 |
/11 | 255.224.0.0 | 8 (6) | 2097150 |
/12 | 255.240.0.0 | 16 (14) | 1048574 |
/13 | 255.248.0.0 | 32 (30) | 524286 |
/14 | 255.252.0.0 | 64 (62) | 262142 |
/15 | 255.254.0.0 | 128 (126) | 131070 |
/16 | 255.255.0.0 | 256 (254) | 65534 |
/17 | 255.255.128.0 | 512 (510) | 32766 |
/18 | 255.255.192.0 | 1024 (1022) | 16382 |
/19 | 255.255.224.0 | 2048 (2046) | 8190 |
/20 | 255.255.240.0 | 4096 (4094) | 4094 |
/21 | 255.255.248.0 | 8192 (8190) | 2046 |
/22 | 255.255.252.0 | 16384 (16382) | 1022 |
/23 | 255.255.254.0 | 32768 (32766) | 510 |
/24 | 255.255.255.0 | 65536 (65534) | 254 |
/25 | 255.255.255.128 | 131072 (131070) | 126 |
/26 | 255.255.255.192 | 262144 (262142) | 62 |
/27 | 255.255.255.224 | 524288 (524286) | 30 |
/28 | 255.255.255.240 | 1048576 (1048574) | 14 |
/29 | 255.255.255.248 | 2097152 (2097150) | 6 |
/30 | 255.255.255.252 | 4194304 (4194302) | 2 |
Class B
Network Bits | Subnet Mask | Number of Subnets | Number of Hosts |
/16 | 255.255.0.0 | 0 | 65534 |
/17 | 255.255.128.0 | 2 (0) | 32766 |
/18 | 255.255.192.0 | 4 (2) | 16382 |
/19 | 255.255.224.0 | 8 (6) | 8190 |
/20 | 255.255.240.0 | 16 (14) | 4094 |
/21 | 255.255.248.0 | 32 (30) | 2046 |
/22 | 255.255.252.0 | 64 (62) | 1022 |
/23 | 255.255.254.0 | 128 (126) | 510 |
/24 | 255.255.255.0 | 256 (254) | 254 |
/25 | 255.255.255.128 | 512 (510) | 126 |
/26 | 255.255.255.192 | 1024 (1022) | 62 |
/27 | 255.255.255.224 | 2048 (2046) | 30 |
/28 | 255.255.255.240 | 4096 (4094) | 14 |
/29 | 255.255.255.248 | 8192 (8190) | 6 |
/30 | 255.255.255.252 | 16384 (16382) | 2 |
Class C
Network Bits | Subnet Mask | Number of Subnets | Number of Hosts |
/24 | 255.255.255.0 | 0 | 254 |
/25 | 255.255.255.128 | 2 (0) | 126 |
/26 | 255.255.255.192 | 4 (2) | 62 |
/27 | 255.255.255.224 | 8 (6) | 30 |
/28 | 255.255.255.240 | 16 (14) | 14 |
/29 | 255.255.255.248 | 32 (30) | 6 |
/30 | 255.255.255.252 | 64 (62) | 2 |
Class D
CIDR Block | Supernet Mask | Number of Class C Addresses | Number of Hosts |
/14 | 255.252.0.0 | 1024 | 262144 |
/15 | 255.254.0.0 | 512 | 131072 |
/16 | 255.255.0.0 | 256 | 65536 |
/17 | 255.255.128.0 | 128 | 32768 |
/18 | 255.255.192.0 | 64 | 16384 |
/19 | 255.255.224.0 | 32 | 8192 |
/20 | 255.255.240.0 | 16 | 4096 |
/21 | 255.255.248.0 | 8 | 2048 |
/22 | 255.255.252.0 | 4 | 1024 |
/23 | 255.255.254.0 | 2 | 512 |
What is the total number of usable host IP addresses on a network with a 26 mask?
Subnet Cheat Sheet – 24 Subnet Mask, 30, 26, 27, 29, and other IP Address CIDR Network References.
How many IP addresses are in a 24?
The /24 subnet will be assigned to the Internet Access Service used by your equipment. In case of multiple services, you will need to select on which one you will be use it. Out of all 256 IPs in this /24 subnet, only 253 can be used. The first IP address from this subnet (ex: .
How many IP addresses are available for hosts?
If you don't know, there are a total of 4,294,967,296 possible IP addresses in IPv4.
How many host IDs does a 20 network support?
How many host IDs does a /20 network support? 8.