Wildcard Mask Calculator
Enter a subnet mask or wildcard mask to instantly convert between the two formats for Cisco ACL and OSPF configuration. Get the inverse mask, matching IP range, and access list notation — essential for writing Cisco IOS access control lists, OSPF network statements, and router filter rules.
Subnet Mask to Wildcard
Wildcard Mask
0.0.0.255
Wildcard to Subnet Mask
Subnet Mask
255.255.255.0
CIDR Notation
/24
Total Addresses
256
Usable Hosts
254
Binary Representation
Subnet Mask:11111111.11111111.11111111.00000000
Wildcard Mask:00000000.00000000.00000000.11111111
Cisco Command Examples
! ACL Example:
access-list 10 permit 192.168.1.0 0.0.0.255
! OSPF Example:
network 192.168.1.0 0.0.0.255 area 0
Common Wildcard Masks
| CIDR | Subnet Mask | Wildcard Mask | Hosts |
|---|---|---|---|
| /8 | 255.0.0.0 | 0.255.255.255 | 16,777,214 |
| /16 | 255.255.0.0 | 0.0.255.255 | 65,534 |
| /24 | 255.255.255.0 | 0.0.0.255 | 254 |
| /25 | 255.255.255.128 | 0.0.0.127 | 126 |
| /26 | 255.255.255.192 | 0.0.0.63 | 62 |
| /27 | 255.255.255.224 | 0.0.0.31 | 30 |
| /28 | 255.255.255.240 | 0.0.0.15 | 14 |
| /29 | 255.255.255.248 | 0.0.0.7 | 6 |
| /30 | 255.255.255.252 | 0.0.0.3 | 2 |
| /32 | 255.255.255.255 | 0.0.0.0 | 1 |
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