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CIDR Calculator
Calculate IP ranges, subnet masks, and host counts from CIDR notation.
Enter an IPv4 address with CIDR prefix (e.g., 10.0.0.0/8). Press Enter or Ctrl+Enter to calculate.
Common Subnets:
Subnet Overlap Checker
Keyboard shortcuts: Enter or Ctrl+Enter to calculate, Escape to clear.
About CIDR Calculator
The CIDR Calculator computes comprehensive subnet details from CIDR (Classless Inter-Domain Routing) notation — the standard format (e.g., 192.168.1.0/24) for specifying IP address blocks in network engineering, cloud infrastructure, and security policy configuration. Given any IPv4 or IPv6 CIDR block, it instantly calculates the network address, broadcast address, subnet mask (in dotted-decimal and binary), first/last usable host IPs, total host count, and wildcard mask. CIDR replaced the older class-based addressing system and is the foundation of all modern IP routing.
How to Use
Enter an IP address with CIDR prefix length (e.g., 10.0.0.0/8 or 172.16.0.0/12) into the input field. The calculator immediately displays all subnet parameters: network address, broadcast address, usable IP range, subnet mask, wildcard mask, total addresses, and usable hosts. Use the subnet splitter to divide a CIDR block into equally-sized smaller subnets.
Common Use Cases
- Planning IP address allocation and subnetting for new enterprise network deployments and data center infrastructure
- Configuring AWS VPC CIDR blocks, Azure VNet address spaces, and GCP subnetwork ranges for cloud infrastructure provisioning
- Writing firewall rules and security group policies by determining the exact IP range covered by a CIDR notation block
- Verifying whether a specific IP address falls within a given CIDR range for network access control and routing table analysis
- Subdividing a /16 or /8 block into department-specific /24 or /26 subnets for network segmentation and broadcast domain isolation
Frequently Asked Questions About CIDR Calculator
What is CIDR Calculator?
CIDR Calculator is a free online tool on akousa.net, a platform with 559+ browser-based utilities. Calculate IP ranges, subnet masks, and host counts from CIDR notation. No installation is required.
How do I use CIDR Calculator?
Simply open CIDR Calculator on akousa.net, enter or upload your data, configure any options, and click the action button. Results appear instantly in your browser.
Is CIDR Calculator free?
Yes, the core CIDR Calculator experience is free to use without signup. All 559+ tools remain available for everyday use, while Akousa Pro adds optional premium platform features and ad-free browsing.