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/28 Subnet Mask

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A /28 subnet mask is 255.255.255.240, with 16 addresses and 14 usable hosts.

CIDR prefix/28
Subnet mask255.255.255.240
Subnet mask (binary)11111111.11111111.11111111.11110000
Wildcard mask0.0.0.15
Network bits / host bits28 / 4
Total addresses16
Usable hosts14
/28 subnets in a /81,048,576
/28 subnets in a /164,096
/28 subnets in a /2416

The mask ends 4 bits into octet 4, so blocks step in increments of 16 in that octet. Sixteen per /24, with 14 usable hosts each. Common for small server groups and DMZ segments.

Try it with an address

Example /28 subnets in 192.168.1.0/24

Network First usable host Last usable host Broadcast
192.168.1.0/28 192.168.1.1 192.168.1.14 192.168.1.15
192.168.1.16/28 192.168.1.17 192.168.1.30 192.168.1.31
192.168.1.32/28 192.168.1.33 192.168.1.46 192.168.1.47
192.168.1.48/28 192.168.1.49 192.168.1.62 192.168.1.63
192.168.1.64/28 192.168.1.65 192.168.1.78 192.168.1.79
192.168.1.80/28 192.168.1.81 192.168.1.94 192.168.1.95
192.168.1.96/28 192.168.1.97 192.168.1.110 192.168.1.111
192.168.1.112/28 192.168.1.113 192.168.1.126 192.168.1.127

Frequently asked questions

What is the subnet mask for /28?

A /28 subnet mask is 255.255.255.240. In binary that is 11111111.11111111.11111111.11110000: 28 network bits followed by 4 host bits. The wildcard mask is 0.0.0.15.

How many usable hosts are in a /28?

A /28 holds 16 addresses in total. Subtracting the network and broadcast addresses leaves 14 usable hosts.

How many /28 subnets fit in a /24?

A /24 divides into 16 subnets of size /28, because each extra mask bit doubles the number of subnets.

Other prefix lengths

← /27 Full CIDR chart /29 →

Calculate this over HTTP: curl https://networkcalc.com/api/ip/192.168.1.0/28. See the Subnet Calculator API.