What is a CIDR to IP Range Calculator?
A CIDR to IP range calculator converts CIDR (Classless Inter-Domain Routing) notation into a complete list of IP addresses contained within that network block. When you enter a CIDR notation like 192.168.1.0/24, this tool shows you every IP address from 192.168.1.0 through 192.168.1.255, helping you understand exactly which addresses are included in the specified range.
This tool is essential for network administrators, security professionals, and anyone who needs to understand the exact scope of a CIDR block. Whether you're configuring firewall rules, setting up access control lists, or planning IP address allocation, knowing the precise range of addresses is crucial. For general CIDR calculations, you can also use our CIDR calculator which provides additional network details.
Practical Use Case
When configuring a firewall rule to block traffic from 10.0.0.0/8, this calculator shows you that you're blocking over 16 million addresses (10.0.0.0 through 10.255.255.255). Understanding the scope prevents accidentally blocking too much or too little traffic.
How to Use the CIDR to IP Range Calculator
Using this calculator is straightforward:
Step 1: Enter CIDR Notation
Type your CIDR block in the format IP_ADDRESS/PREFIX (e.g., 192.168.1.0/24). The IP address should be a valid IPv4 address, and the prefix should be between 0 and 32. You can use the quick example buttons to see common CIDR ranges.
Step 2: Review the Range Details
The calculator displays the first IP (network address), last IP (broadcast address), total addresses, and usable hosts. The range is shown in both hyphenated format (first - last) and as a browsable list.
Step 3: Browse or Export the IP List
For smaller ranges (up to 1,024 addresses), the full IP list is displayed. You can copy the list to clipboard or download it as a CSV file for use in spreadsheets, scripts, or other tools. Larger ranges show a warning to prevent browser performance issues.
Understanding the Results
Network Address (First IP)
The first IP address in the range is the network address. This address identifies the network itself and cannot be assigned to any host device. In the list, it's marked as "Network" to distinguish it from usable addresses. Learn more about network addresses with our network address calculator.
Broadcast Address (Last IP)
The last IP address in the range is the broadcast address. It's used to send data to all hosts on the network simultaneously. Like the network address, it cannot be assigned to individual hosts. Our broadcast address calculator provides more details on broadcast addresses.
Usable Host Range
The usable hosts are all addresses between the network and broadcast addresses. These are the IPs you can actually assign to devices. For a /24 network with 256 total addresses, you have 254 usable (256 - 2 for network and broadcast).
Common CIDR Ranges and Their Sizes
Understanding how CIDR prefixes translate to address counts helps in network planning:
| CIDR | Total IPs | Usable Hosts | Example Range |
|---|---|---|---|
| /30 | 4 | 2 | 192.168.1.0 - 192.168.1.3 |
| /29 | 8 | 6 | 192.168.1.0 - 192.168.1.7 |
| /28 | 16 | 14 | 192.168.1.0 - 192.168.1.15 |
| /27 | 32 | 30 | 192.168.1.0 - 192.168.1.31 |
| /26 | 64 | 62 | 192.168.1.0 - 192.168.1.63 |
| /25 | 128 | 126 | 192.168.1.0 - 192.168.1.127 |
| /24 | 256 | 254 | 192.168.1.0 - 192.168.1.255 |
| /23 | 512 | 510 | 192.168.0.0 - 192.168.1.255 |
| /22 | 1,024 | 1,022 | 192.168.0.0 - 192.168.3.255 |
| /16 | 65,536 | 65,534 | 192.168.0.0 - 192.168.255.255 |
| /8 | 16,777,216 | 16,777,214 | 10.0.0.0 - 10.255.255.255 |
Practical Applications
Firewall Configuration
When creating firewall rules, you often specify allowed or blocked IP ranges using CIDR notation. This calculator helps verify that your rules cover exactly the intended addresses. For example, blocking 192.168.100.0/28 blocks only 16 addresses (192.168.100.0-15), not the entire 192.168.100.x subnet.
Access Control Lists (ACLs)
Network ACLs use CIDR ranges to permit or deny traffic. Understanding the exact IP range ensures your ACLs don't accidentally allow unwanted traffic or block legitimate users. The calculator's IP list can be used to verify individual addresses within the range.
DHCP Scope Planning
When configuring DHCP servers, you need to define the range of addresses the server can assign. This calculator shows the usable range (excluding network and broadcast addresses) to help define appropriate DHCP scopes.
Security Scanning
Security professionals often need to scan specific IP ranges for vulnerabilities. Export the IP list to feed into scanning tools, ensuring comprehensive coverage of all addresses in a target network.
Cloud Network Planning
Cloud platforms like AWS, Azure, and GCP use CIDR for VPC and subnet definitions. When setting up VPC peering or defining security groups, understanding the exact IP range prevents conflicts and ensures proper connectivity.
Example: AWS Security Group
Creating an AWS security group rule to allow SSH from your office network:
- Office CIDR:
203.0.113.0/28 - This allows: 203.0.113.0 - 203.0.113.15 (16 addresses)
- Your actual hosts: 203.0.113.1 - 203.0.113.14 (14 usable)
Using this calculator confirms you're allowing exactly the right range.
Working with IP Lists
The calculator provides options to work with the generated IP list:
Copy to Clipboard
Click "Copy List" to copy all IP addresses as plain text, one per line. This is useful for pasting into scripts, configuration files, or documentation.
Download as CSV
Download the complete list as a CSV file with columns for IP address and type (Network, Host, or Broadcast). Import into Excel, Google Sheets, or any tool that accepts CSV data.
List Limitations
For performance reasons, the full IP list is only displayed for ranges up to 1,024 addresses (/22 and smaller). Larger ranges show summary information and the first/last addresses. You can still see the total count and range boundaries for any size network.
For comprehensive subnet planning including multiple networks, use our VLSM calculator. To visualize subnet divisions graphically, try our visual subnet calculator.
Converting Between Range and CIDR
Sometimes you have a start and end IP address and need to find the CIDR notation that represents that range. While this calculator converts CIDR to ranges, the reverse process requires finding the appropriate prefix length that encompasses both addresses. For subnet mask conversions, use our netmask to CIDR converter.