What is a /28 subnet? 16 IPs for small server groups and point-to-point links

A /28 subnet, written as 255.255.255.240, provides 16 total addresses with 14 usable for hosts. This is the go-to size for small server groups, DMZ segments, and cloud subnets where you need isolation without wasting address space.

CIDR

/28

Class C

Total addresses

14 usable for hosts

Network size

Small Networks

Up to 254 hosts

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IPv4/IPv6 Subnet Calculator

Calculate network address, broadcast address, and usable IP ranges.

IP Address

Subnet Mask (CIDR)

Results

Network Address

192.168.1.0

Broadcast Address

192.168.1.255

Usable Host Range

192.168.1.1 - 192.168.1.254

Total Usable Hosts

254

Subnet Mask

255.255.255.0

Binary Subnet Mask

11111111.11111111.11111111.00000000

Interactive Bit-Level Visualizer

Click any bit to flip it and instantly update the IP address. Network bits are indigo, host bits are pink.

How this is calculated

With 14 usable addresses, a /28 fits a small cluster of web servers, a database HA pair with monitoring, or a dedicated management network. Cloud providers like AWS and Azure let you create /28 subnets within a VPC or VNet, which is useful for security groups that isolate specific application tiers. The subnet mask 255.255.255.240 means each /28 block increments the last octet by 16 (e.g., .0-.15, .16-.31, .32-.47).

Verdict

A /28 is the smallest subnet you should provision for anything that might grow. With 14 usable IPs, you have room for the current servers plus a few spares for scaling or HA failover. For point-to-point links where you need exactly 2 addresses, use a /30 or /31 instead.