pjhtech Tools
Address planning

Wildcard Mask Calculator

Convert between a contiguous subnet mask and its inverse ACL wildcard.

Input

Reset restores the example inputs.

Local calculation · inputs are not sent to a server.

Result

Calculating the example…

Choose whether your input is a subnet mask or an ACL wildcard, then enter that mask. Use the Wildcard result only in a command that asks for an inverse mask.

Example: 255.255.255.192 becomes 0.0.0.63. With an aligned network of 10.42.7.64, this wildcard covers the same address set as /26.

This tool supports contiguous CIDR-derived wildcards. Some ACL implementations accept noncontiguous wildcards; those cannot be represented by one CIDR and are rejected here. Confirm the vendor command uses wildcard semantics.

References