IP Subnet Calculator

Subnet: A logical subdivision of an IP network is a subnetwork (subnet). Subnetting is the process of separating a network into two or more networks.

Subnet Mask: The range of IP addresses that can be utilized within a network or subnet is defined by a subnet mask. Furthermore, it divides an IP address into two parts: network bits and host bits.

A subnet mask is a 32-bit number that contains all 0s for host bits and all 1s for network bits. In this way, the IP address divides into network and host addresses by the subnet mask. The "255" address is always assigned to a broadcast address, while the "0" address is always assigned to a network address.

IP Subnet Calculator CIDR Notation

There were three main subnet masks in the early days of the Internet, all of which used multiples of 8 bits of ‘1’s in the mask. As seen in the table, they were dubbed Class A, Class B, and Class C networks.

The issue with this system is the big jumps in the number of hosts/networks. That is the number of hosts per network is chosen in a haphazard manner.

This problem is solved by Classless Inter-Domain Routing (CIDR), which does away with the class model and allows the network designer to give any amount of bits to the network prefix, allowing for a wider range of host numbers per network.

A forward-slash ( / ) followed by the number of bits is a way to represent the number of bits in the network prefix. Because it uses the first 8 bits of the network mask, a Class A network is represented as ‘/8’. The following table shows the CIDR notation and the number of useable hosts per subnet:

How to Calculate IP Subnet Mask Manually?

The manual process of calculating theIP subnet mask problems is explained in the simple steps below:

1. First, find out the network class of the IP address.
2. Now, calculate the number of bits, which are used to define the subnets.
3. The formula for calculating the number of bits is Number of bits = Log₂(Number of subnets + 2).
4. Apply the values in the formula and determine the Number of Bits.
5. Using the calculated bits, compose the subnet mask in binary form.
6. Use the binary classification method for composing subnet masks.
7. Now, substitute the subnet bits in the binary classification.
8. For determining the IP subnet mask convert the binary values to their equivalent decimal values.
9. Finally, the determined value is the desired IP Subnet Mask.

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Solved Example on IPv4 & IPv6 Subnet Calculator

Example:

Consider an IP address 192.34.128.93 which belongs to the network with 6 subnets. Calculate the Number of bits, to define the subnets.

Solution:

Given here is 6 subnets,

Now by applying the value in the IP Subnet Formulae, we get:

Number of Bits = Log₂(Number of subnets + 2)

= Log₂(6+2) = 3 bits

IP Address 192.34.128.93 falls on Class C, whose Binary Classification is 11111111.11111111.11111111.00000000.

Substituting the bits 11111111.11111111.11111111.11100000.

Converting the bits into the equivalent decimal values, 11111111.11111111.11111111.11100000 with the help of the rules,

we get,

11111111 = 255

11111111 = 255

11111111 = 255

11100000 - (128 x 1) + (64 x 1) + (32 x 1) + (16 x 1) + (8 x n) + (4 x 0) + (2 x 0) + (1 x 0) = 224

Hence, the IP Subnet Mask = 255.255.255.224

FAQs on Online IP Subnet Calculator

1. What is a 255.255 255.0 subnet?

It is a class C network, which means that 24 bits are used for the network. It can also be represented as /24 following IP address.

2. How do you calculate hosts per subnet?

To calculate hosts per subnet we can use the formula 2^x-2, where x denotes the number of host IDs in bits.

3. How do I find my IP range subnet?

To find the IP range subnet, first, you need to calculate the subnet length. Then, add 2 to the power of the subnet length to find the number of hosts. Using this information the IP range subnet can be determined.