Wildcard Mask
Paste a mask (255.255.255.0), a CIDR (/24) or a wildcard (0.0.0.255) — it is auto-detected — and get the wildcard, the mask, the CIDR and the binary of the 32 bits. With an optional network it builds the Cisco ACL and OSPF examples. Nothing is sent to any server.
Binary of the 32 bits
bits set to 1 bits set to 0
Configuration examples
Type a network above to use it in the commands.
What the wildcard is · how it is calculated
1. The wildcard (or inverse
mask) is the bitwise NOT of the network mask: per octet,
255 − octet.
2. A 0 bit in the wildcard
means "must match"; a 1 bit means
"don't care". It is the opposite of the mask.
3. Cisco uses the wildcard in
ACLs and in OSPF
(network <network> <wildcard> area 0).
4. A valid mask has the 1s
followed by the 0s (contiguous); the CIDR
(/n) is the number of bits set to 1. A non-contiguous
wildcard is legal in an ACL but does not map to a CIDR.
Runs locally in your browser · no sign-up · nothing leaves your browser.