What is a wildcard mask?

A wildcard mask is a 32-bit pattern used by Cisco IOS where 0 means “must match” and 1 means “ignore.” It is usually the inverse of a contiguous subnet mask.

How do I calculate a wildcard mask?

Subtract each subnet-mask octet from 255, or invert every bit. Example: 255.255.255.0 becomes 0.0.0.255. This calculator does that conversion for you.

What is the wildcard mask for /24?

A /24 uses subnet mask 255.255.255.0, so the wildcard mask is 0.0.0.255.

How is a wildcard mask different from a subnet mask?

A subnet mask marks network bits with ones. A wildcard mask marks “don’t care” bits with ones. They describe related ideas but read in opposite directions.

Where are wildcard masks used in Cisco ACLs?

In standard and extended ACLs, the wildcard follows the address you want to match, for example access-list 10 permit 192.168.10.0 0.0.0.255.

What is Wildcard Mask Calculator?

A free online tool that converts between subnet masks/CIDR and Cisco wildcard masks, with ACL and OSPF examples for practice.

How does the Wildcard Mask Calculator work?

It validates your mask or prefix, inverts the bits to build the wildcard (or reverses that process), and shows sample Cisco commands.

How do I use the Wildcard Mask Calculator?

Pick a conversion direction, enter a mask, CIDR, or wildcard, and copy the results into your notes or lab.

Is this Wildcard Mask Calculator free to use?

Yes. It is free for beginners, CCNA students, IT students, and network engineers with no registration.

Can I use the Wildcard Mask Calculator on mobile?

Yes. The page works on phones and tablets so you can check ACL wildcards away from your desk.

Free Wildcard Mask Calculator Online, Cisco ACL & OSPF

Free Wildcard Mask Calculator Online, Cisco ACL & OSPF | Binary Tech