Subnet Mask
/18 Subnet Mask
A /18 prefix means the subnet mask is 255.255.192.0. It has 14 host bits, giving 16,384 total addresses and 16,382 usable hosts.
/18 at a glance
| Property | Value |
|---|---|
| CIDR prefix | /18 |
| Subnet mask | 255.255.192.0 |
| Wildcard mask | 0.0.63.255 |
| Total addresses | 16,384 |
| Usable hosts | 16,382 |
| Host bits | 14 |
How it is calculated
A /18 sets the first 18 bits to 1 (network) and the remaining 14 bits to 0 (host). Usable hosts = 214 − 2 = 16,382.
The wildcard mask 0.0.63.255 is the inverse — used in Cisco ACLs and OSPF network statements.
Frequently asked questions
What is a /18 subnet mask?
A /18 equals 255.255.192.0 in dotted decimal (wildcard 0.0.63.255). It provides 16,384 total addresses and 16,382 usable hosts.
How many hosts are in a /18?
A /18 has 14 host bits, so it supports 16,382 usable hosts.
What is the wildcard mask for /18?
The wildcard (inverse) mask for /18 is 0.0.63.255, used in Cisco ACLs and OSPF statements.
Related
Learn networking hands-on
Master IP addressing, subnetting and Cisco configuration on real lab devices with placement support at Attila Technologies, Ahmedabad.