Wildcard Mask Calculator

Get inverse mask for ACLs. Enter prefix or subnet mask.

Prefix or mask

Wildcard mask0.0.0.255

Subnet mask255.255.255.0

Prefix/24

How to read the result

Wildcard = 255.255.255.255 − mask. Used in Cisco ACLs and OSPF network statements.

Example

/24 → wildcard 0.0.0.255

FAQ

Wildcard vs mask?

Mask marks network bits (1s). Wildcard marks host bits (1s). Exact inverse.