IP Subnet Calculator: IPv4 Network Planning

Calculate subnet mask, IP address range, broadcast address, and the number of available hosts for your network configuration in detail.

Input Parameters

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Ready to Calculate

Fill in the required parameters on the left and click calculate to see the detailed results and analysis.

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Basic Guide to Subnetting and IPv4 Network Planning

For a network administrator or IT technician, understanding network division (Subnetting) is a crucial foundational skill. Subnetting allows us to break one large network into several smaller ones that are more efficient, organized, and secure. Our IP Subnet Calculator helps you avoid manual binary calculation errors that are often time-consuming.

Why Is Subnetting Useful?

The subnetting process provides several key advantages in IT infrastructure:

  • 1Reducing Traffic Congestion: By dividing the network, we can limit broadcast traffic only to specific subnets.
  • 2Enhancing Security: Provides ease for admins to apply security policies (Firewalls/ACL) between departments or floors.
  • 3IP Address Optimization: Ensuring that not many IP addresses are wasted, especially when using limited public IPs.

    • Explaining Calculation Result Components

    When you perform a subnet calculation, several technical terms will appear:

  • •Network Address: The first address of a network that cannot be used as a host.
  • •Broadcast Address: The last address in the network used to send data to all hosts within that subnet.
  • •CIDR (Classless Inter-Domain Routing): A more concise subnet mask writing format such as /24.
  • •Subnet Mask: A 32-bit binary number that separates the network address and host address parts.
  • •Host Range: The range of IP addresses that you can assign to devices such as computers, printers, or servers.

    • IP Address Classification (Classful vs. Classless)

    In the past, IP addresses were divided into rigid classes (A, B, C). However, this system was considered inefficient. Now, the IT world uses the Classless (CIDR) system which allows network division into any size according to needs. For example, /24 provides 254 hosts, while /26 only provides 62 hosts.

    Tips for Choosing the Right Subnet Mask

    Always consider future network growth. If your office currently has 20 devices, don't use a /29 subnet (only 6 hosts). Use at least /27 (30 hosts) so that you have spare room for new devices without having to overhaul the entire IP scheme.

    How to Use This Subnet Calculator

    Enter your IPv4 IP address in the input field. Select the desired mask bit (CIDR) value from the selection menu. The calculator will automatically dissect that IP and display full Subnet Mask details, Network Address, Broadcast Address, and the maximum number of Hosts you can connect.

    ? Frequently Asked Questions

    Q What is CIDR notation?

    CIDR (Classless Inter-Domain Routing) is a method of writing a subnet mask with a specific number of bits; for example, /24 is equal to subnet mask 255.255.255.0.

    Q How many hosts are in a /24 subnet?

    A /24 subnet has a total of 256 IP addresses. However, because 1 address is used for the network and 1 address for broadcast, the effective number of hosts that can be used is 254.

    Q Can I use subnetting on IPv6?

    Yes, IPv6 also has a subnetting system, but due to its massive address space (128-bit), this calculator is specifically designed for the more common IPv4 needs.

    Q What is the difference between Public IP and Private IP?

    Private IPs (such as 192.168.x.x) are used within local networks. Public IPs are unique addresses recognized throughout the global internet network.

    Q Why can't I use the start and end IP in a subnet?

    The first address (Network ID) is used as the identity of that network, and the last address (Broadcast ID) is used as the destination address when a device wants to communicate with all other devices in its subnet.