Subnet Calculator

IP Address Subnet Mask

Start Host Address
End Host Address
Max No. of Hosts
Network Address
Broadcast Address
Network Class
Network Address Size Bits
Host Address Size Bits
IP Address Binary
Network Address Binary
Broadcast Address Binary
Subnet Mask Binary
An image illustrating the step-by-step process of using a Subnet Calculator. The image shows a user entering the IP address and subnet mask into the calculator's input fields. The next step displays the calculator automatically calculating the network address, broadcast address, available host range, and other subnet-related information. This image visually guides the user on how to use the Subnet Calculator, a helpful tool for subnetting IP addresses and determining network information.

An IP subnet calculator helps network administrators efficiently manage networks with a large number of connected devices. Dividing these networks into smaller subnets is crucial for organization and efficient resource allocation.

Key Benefits of Using a Subnet Calculator

  • Allows network segmentation without headache of manual calculation
  • Visualizes address space allocation cleanly for documentation
  • Models different IP schemes and sizes for future growth planning
  • Ensures optimum address efficiency without waste
  • Simplifies subnet troubleshooting by clarifying routing issues
  • Saves time over manual subnet math

What is a Subnet Calculator?

A subnet calculator is an online tool used to divide or subset bigger networks and allocate addresses. By entering details like:

  • IP address
  • Subnet mask
  • CIDR notation

The calculator automates the complex math of subnetting. It outputs configured subnet parameters like:

  • Host and network address ranges
  • Number of available hosts
  • Broadcast addresses
  • Binary conversions

Working with subnet masks manually to carve out custom IP address spaces and allot addresses is tricky. Web-based subnet calculators simplify everything.

How Do I Find My IP Subnet?


  1. Find your IP address and subnet mask. You can find these on most devices by checking the network settings or status. For example, in Windows you can open the Command Prompt and type "ipconfig" to see your network configuration details.
  2. Your IP address will be listed next to something like "IPv4 Address" and your subnet mask next to "Subnet Mask." It will look something like this example: IP address: Subnet mask: ‎
  3. Enter your IP address and subnet mask into an online subnet calculator. There are many free subnet calculators available with a quick online search.
  4. The subnet calculator will automatically determine and display your subnet based on the IP address and mask.

Why Subnet Networks?

There are a few key reasons to use a subnet calculator to divide larger networks:

Organization - Segment servers, users, devices, geography etc. into logical groups for easier management.

Containment - Limit network accessibility and communication between devices and users by group.

Optimization - Right-size address spaces to actual need using flexible Variable Length Subnet Mask (VLSM) rather than waste IPs.

Routing - Improve network traffic directed at specific subnets. Simplifies loads, security, quality of service.

How to Use an IP Subnet Calculator

Using an IP address subnet calculator only takes a few steps:

  1. Enter existing IP address and associated subnet mask
  2. Specify subnet mask bits for desired new network mask
  3. View how subnets are divided and addresses allocated
  4. Optionally adjust to achieve needed host capacity, containment etc.

Calculators produce various output data like:

  • Available host ranges
  • Number of permissible hosts
  • Network and broadcast addresses
  • Netmask binary conversion

And suggest free adjacent IP spaces to subnet further. Adjusting the subnet mask bits or maximum transmission unit and re-calculating lets you iteratively optimize, combine, or divide networks.

Sample Subnet Calculator Usage

Let’s walk through an example:

  1. Enter IP address:
  2. Enter current subnet mask: (/24)

Subnet Calculation Outputs:

  • Address class: C
  • Host size: 256
  • Block size: /24
  • Netmask: 11111111.11111111.11111111.00000000
  1. Adjust subnet mask to: /25 to make two subnets

Subnet Calculation Outputs:

  • 2 usable subnets
  • Each subnet capacity = 128 hosts
  • Subnet 1 range = -
  • Subnet 2 range = -

Using the subnet calculator in this way facilitates visual IP address space segmentation, allocation planning, and documentation.

Frequently Asked Questions (FAQs)

Q1: What is a subnet?

A subnet, short for subnetwork, is a partition of an IP network that allows for efficient and organized management of IP addresses.

Q2: How does subnetting work?

Subnetting involves dividing a large network into smaller subnets, each with its own range of IP addresses. This allows for better network management, improved security, and efficient use of available IP addresses.

Q3: Why is subnetting important?

Subnetting is important for several reasons. It helps in reducing network traffic, improving network performance, enhancing network security by isolating certain devices, and optimizing the use of IP address space within an organization or network.

Read More: What is a subnet? | How subnetting works

                       How To Use Free Subnet Calculator?