CIDR to IPv4 Range & Wildcard Mask Calculator
Compute network boundaries, first/last usable host IPs, and Cisco wildcard masks.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. No data is ever transmitted across the network.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
How to Use CIDR to IPv4 Range & Wildcard Mask Calculator
Type an IPv4 network address with prefix length (e.g. 192.168.1.0/24).
Inspect usable host range (First IP – Last IP), total address capacity, and broadcast address.
Copy the complete subnet specification to configure routers or firewall security groups.
Frequently Asked Questions
What is a Cisco wildcard mask?
A wildcard mask is the inverse of a subnet mask (e.g., netmask 255.255.255.0 has wildcard 0.0.0.255), used in Cisco ACLs and OSPF routing configurations.
Why are the first and last IPs excluded from usable hosts in /24?
The first address is reserved as the Network ID and the last address is reserved as the Subnet Broadcast IP.
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