Wildcard Mask Calculator — Free Online Cisco ACL Tool
Wildcard Mask Calculator
Wildcard Mask Calculator
Convert CIDR or subnet mask to a Cisco ACL wildcard mask
Subnet Mask
255.255.255.0
Wildcard Mask
0.0.0.255
CIDR Prefix
/24
Network
192.168.1.0
Sample ACL
access-list 10 permit 192.168.1.0 0.0.0.255
OSPF network
network 192.168.1.0 0.0.0.255 area 0
Wildcard = inverse of subnet mask. 0 bits must match; 1 bits are don’t-care — used heavily in Cisco ACLs and OSPF.
Free Online Wildcard Mask Calculator
Convert subnet masks and CIDR to Cisco wildcard masks for ACLs and OSPF — a simple wildcard mask calculator tool for beginners and CCNA students. Related: Subnet Mask Calculator.
How to calculate a wildcard mask
Enter a network IP and prefix. The calculator inverts the subnet mask (for /24 → 0.0.0.255) and shows sample ACL and OSPF lines used in Cisco networking.
Wildcard Mask FAQ
Need a free wildcard mask calculator for ACL labs? This wildcard mask calculator online free tool runs in your browser.