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IP Range to CIDR Converter Tool - Free Online Network Calculator

First Published: 2025-10-01
Last Updated: 2025-10-01

Free IP Range to CIDR Converter with instant browser-based calculation. All conversion processes are performed entirely within your browser - your IP addresses never leave your device.

⚠️ IMPORTANT DISCLAIMER:

This tool is provided for educational and reference purposes only, "AS IS" without any warranties.
We accept NO responsibility for network misconfigurations, routing errors, or security issues.
Always verify CIDR calculations before applying them to production networks.
Incorrect CIDR configurations can cause network outages or security vulnerabilities.
DO NOT use this tool for critical network infrastructure without professional verification.
Always test network changes in a safe environment before production deployment.
By using this tool, you accept FULL responsibility for all outcomes and consequences.

Privacy & Accuracy: This tool operates entirely within your browser using client-side JavaScript. During the conversion process, no data is transmitted to servers, and all calculations happen locally on your device. Even if our website goes offline, the tool will continue to work once loaded. However, accuracy depends on correct input. Always double-check results before using them in network configurations.

IP Range (format: start - end or start end):

Start IP Address:

End IP Address:

CIDR Notation Result:

How to Use This CIDR Converter Tool

Enter IP Range: Type the IP range using "192.168.0.0 - 192.168.0.255" or "192.168.0.0 192.168.0.255" format, or enter Start/End IPs separately
Click Convert: Click "Convert to CIDR" button to calculate the CIDR notation
View Result: The CIDR notation will be displayed in the result area
Copy Result: Use "Copy Result" button to copy the CIDR notation to clipboard

Pro Tip: Use the example links below to see the tool in action.

About CIDR Notation

CIDR (Classless Inter-Domain Routing) is a method for representing IP address ranges using a compact notation. The format consists of an IP address followed by a slash and a prefix length (e.g., 192.168.0.0/24).

Format: IP address + "/" + prefix length
Example: 192.168.0.0/24 represents 256 IP addresses (192.168.0.0 to 192.168.0.255)
Requirements: The IP range must contain a power of 2 number of addresses (256, 512, 1024, etc.)
Network Address: The starting IP must be a valid network address for the calculated prefix length

Quick Examples (Click to auto-fill)

192.168.0.0 - 192.168.0.255 → 192.168.0.0/24 (256 addresses)

10.0.0.0 - 10.0.3.255 → 10.0.0.0/22 (1,024 addresses)

172.16.0.0 - 172.16.15.255 → 172.16.0.0/20 (4,096 addresses)

Why CIDR Notation Matters

Key Requirements for Valid CIDR Conversion

The number of IP addresses in the range must be a power of 2 (256, 512, 1024, 2048, 4096, etc.)
The starting IP address must be a valid network address for the calculated prefix length
Both IP addresses must be valid IPv4 addresses in the format xxx.xxx.xxx.xxx
The ending IP address must be greater than or equal to the starting IP address

Features:

🔄 Instant Conversion: Convert IP ranges to CIDR notation in real-time
🖥️ Client-Side Processing: All calculations performed locally in your browser
✅ Validation: Automatic validation of IP addresses and ranges
📋 Easy Copy: One-click copy of results to clipboard
📱 Mobile Friendly: Responsive design works on all devices
🔒 Privacy First: Your IP addresses never leave your device
✏️ Flexible Input: Enter range as "start - end", "start end", or use separate fields

Common Use Cases:

Network Configuration: Convert IP ranges to CIDR for router and firewall rules
Cloud Infrastructure: Define VPC subnets and security groups
Documentation: Document network architecture in CIDR notation
IP Address Management: Organize and allocate IP address blocks

References:
Tech Blog with curated related content
Web Tools Collection

Written by Hidekazu Konishi