Subnet Mask, CIDR Prefix & Wildcard Mask Converter
Instant radix and notation conversion across all /0 to /32 IPv4 subnet classes.
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 Subnet Mask, CIDR Prefix & Wildcard Mask Converter
Click any row in the /0 to /32 reference table or search for a specific mask.
View CIDR prefix, dotted decimal mask, Cisco wildcard mask, and total/usable host capacities.
Copy the complete subnet specification to configure network routers and firewalls.
Frequently Asked Questions
What is the relationship between CIDR prefix and subnet mask?
The CIDR prefix represents the number of leading binary '1' bits in the 32-bit subnet mask (e.g. /24 has twenty-four 1s, resulting in 255.255.255.0).
How is a Cisco wildcard mask derived?
Subtract each octet of the subnet mask from 255 (e.g., 255.255.255.255 - 255.255.255.0 = 0.0.0.255).
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