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IP Subnet Calculator

Calculate IP subnet details including network address, broadcast address, and host range using CIDR notation.

IP Subnet Calculator

Calculate network range, broadcast address, and usable hosts.

Understanding the IP Subnetting

Subnetting is the practice of dividing a network into two or more smaller networks. It improves routing efficiency, enhances security, and reduces network congestion by limiting broadcast traffic to smaller segments.

Guide

How to use the IP Subnetting

  • 1Enter the base IP address you wish to subnet (e.g., 192.168.1.0).
  • 2Input the CIDR prefix length (e.g., 24 for a standard Class C network).
  • 3The calculator will instantly determine the subnet mask and host capacity.
  • 4Review the network and broadcast addresses to define your subnet boundaries.
Applications

Common Use Cases

Designing corporate network topologies with logical department separation.
Configuring virtual local area networks (VLANs) in Managed Switches.
Allocating static IP ranges for servers, printers, and IoT devices.
Optimizing router tables by summarizing routes through CIDR notation.

The Maths Behind the Calculation

Hosts = 2^(32 - CIDR) - 2

Usable hosts exclude the network address (all 0s) and broadcast address (all 1s) in the host portion of the bits.

Knowledge Base

Frequently Asked Questions

What is CIDR notation?

Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and IP routing. It replaces the old Class A, B, and C system with a more flexible prefix length (e.g., /24).

Why are there 2 unusable hosts per subnet?

In every subnet, the first address is reserved as the Network Address, and the last address is reserved as the Broadcast Address for that segment.

What is a subnet mask?

A subnet mask is a 32-bit number used to identify the network and host portions of an IP address. It filters which bits belong to the network versus the specific machine.

What is the host range?

The host range encompasses all valid IP addresses that can be assigned to actual devices (PCs, routers, phones) within a specific subnet.

Regional Notice: United States

"Federal tax estimates are based on 2024 brackets. Consult a tax professional for official filing."