Wildcard Mask to Subnet Calculator — Cisco ACL Tool

A wildcard mask to subnet calculator applies standard IPv4 subnet math (RFC 950 / CIDR) to compute network boundaries, masks, and host counts without manual binary conversion.

You enter IPv4 addresses, masks, or CIDR notation. The calculator bitwise-ANDs the address with the mask to find the network ID, then derives broadcast, wildcard, and host ranges.

Use it during CCNA study, VPC design, firewall rule documentation, IPAM planning, and troubleshooting when you need quick confirmation of subnet boundaries.

Yes. VSPIC runs calculations in your browser with no account required.

These calculators focus on IPv4. For IPv6 prefix planning, use our IPv6 Test and IP Subnet Calculator IPv6 tab.

CIDR writes the prefix length after a slash (e.g. /24). It replaces legacy classful networks and is used in routing tables worldwide.

A subnet mask marks which bits belong to the network portion. A /24 equals 255.255.255.0 with 254 usable hosts in typical subnets.

Yes. RFC 1918 addresses (10.x, 172.16–31.x, 192.168.x) use the same subnet mathematics as public space.

Set all host bits to 1 in the subnet — bitwise OR of network address with the inverted mask.

Variable Length Subnet Masking uses different prefix lengths within one parent network to minimize wasted addresses.

Enter subnet mask or CIDR — the wildcard mask to subnet calculator computes the bitwise inverse for ACL fields and shows a sample permit line.

The wildcard is the bitwise inverse of the subnet mask: 255.255.255.0 inverts to 0.0.0.255.