CIDR Calculator: IP Range Converter

Instantly convert CIDR notation into a full IP range. Find your network address, broadcast address, and usable hosts for any subnet.

AI Overview

CIDR (Classless Inter-Domain Routing) is a method used to allocate IP addresses and route packets. A CIDR Calculator takes a block like 192.168.1.0/24 and defines exactly which IPs belong to that network. It is essential for cloud architecture (AWS VPC), setting up firewalls, and managing corporate subnets.

What is CIDR Notation?

CIDR (Classless Inter-Domain Routing) is a compact way to represent an IP address and its associated routing prefix. It consists of an IP address, a slash, and a number (the prefix). For example, /24 indicates that the first 24 bits of the address are the network portion, leaving 8 bits for host addresses.

Quick Tip: A /24 subnet is the most common for home and small business networks, providing 254 usable IP addresses.

How to Calculate IP Ranges

To find the range of a CIDR block, you need to identify the Network Address (the start) and the Broadcast Address (the end). The IPs in between these two are the Usable Hosts that you can assign to computers, printers, and servers.

Why Use a CIDR Calculator?

  • Cloud Planning: Correctly size your AWS VPC or Azure subnets to avoid running out of IPs.
  • Security: Define precise firewall rules by allowing only specific CIDR ranges.
  • Network Auditing: Identify exactly which devices belong to which segment of your office network.
  • Error Prevention: Avoid manual binary math mistakes that can cause routing conflicts.

Frequently Asked Questions

What is the difference between /24 and /16?
A /24 provides 254 usable IPs, while a /16 provides 65,534. The smaller the prefix number, the larger the network.

Why are there 2 fewer usable hosts than total IPs?
In every subnet, the first IP is reserved for the network identifier and the last IP is reserved for broadcasting data to all hosts.

Can I use this for IPv6?
This specific calculator focuses on IPv4. IPv6 uses a 128-bit space and is typically handled with /64 subnets.