Networking / FREE BROWSER TOOL
Wildcard Mask Calculator
Convert an IPv4 CIDR prefix into a subnet mask and inverse wildcard mask for ACL and network configuration planning.
✓ Free to use✓ Runs locally✓ No account needed
Run the tool
Enter the values below to calculate or convert.
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Using the wildcard mask calculator
Enter any IPv4 address with a CIDR prefix. The inverse mask is calculated as 255 minus each subnet mask octet.
Real-world example
Example: /26 equals subnet mask 255.255.255.192 and wildcard mask 0.0.0.63.
Good to know
Wildcard masks appear in many access-control and route matching configurations; always verify the platform’s matching syntax.
This tool is a planning aid, not a substitute for verifying values in vendor documentation or production configurations.