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/18 Subnet Mask

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A /18 subnet mask is 255.255.192.0, with 16,384 addresses and 16,382 usable hosts.

CIDR prefix/18
Subnet mask255.255.192.0
Subnet mask (binary)11111111.11111111.11000000.00000000
Wildcard mask0.0.63.255
Network bits / host bits18 / 14
Total addresses16,384
Usable hosts16,382
/18 subnets in a /81,024
/18 subnets in a /164

The mask ends 2 bits into octet 3, so blocks step in increments of 64 in that octet.

Try it with an address

Example /18 subnets in 192.168.0.0/16

Network First usable host Last usable host Broadcast
192.168.0.0/18 192.168.0.1 192.168.63.254 192.168.63.255
192.168.64.0/18 192.168.64.1 192.168.127.254 192.168.127.255
192.168.128.0/18 192.168.128.1 192.168.191.254 192.168.191.255
192.168.192.0/18 192.168.192.1 192.168.255.254 192.168.255.255

Frequently asked questions

What is the subnet mask for /18?

A /18 subnet mask is 255.255.192.0. In binary that is 11111111.11111111.11000000.00000000: 18 network bits followed by 14 host bits. The wildcard mask is 0.0.63.255.

How many usable hosts are in a /18?

A /18 holds 16,384 addresses in total. Subtracting the network and broadcast addresses leaves 16,382 usable hosts.

How many /18 subnets fit in a /16?

A /16 divides into 4 subnets of size /18, because each extra mask bit doubles the number of subnets.

Other prefix lengths

← /17 Full CIDR chart /19 →

Calculate this over HTTP: curl https://networkcalc.com/api/ip/192.168.1.0/18. See the Subnet Calculator API.