/28 Subnet: Mask 255.255.255.240, 14 Usable Hosts
A /28 subnet has a subnet mask of 255.255.255.240 and contains 16 total IP addresses, of which 14 are usable host addresses (the network and broadcast addresses are reserved). 16 /28 networks fit inside a single /24.
| CIDR notation | /28 |
|---|---|
| Subnet mask | 255.255.255.240 |
| Wildcard mask | 0.0.0.15 |
| Mask in binary | 11111111.11111111.11111111.11110000 |
| Total addresses | 16 (2^4) |
| Usable hosts | 14 |
| Host bits | 4 |
Usable hosts in a /28 by platform
Cloud providers reserve more than the usual two addresses per subnet, so the same /28 gives you fewer usable IPs in the cloud than on a standard LAN.
| Platform | Reserved IPs | Usable hosts |
|---|---|---|
| Standard (network + broadcast) | 2 | 14 |
| AWS VPC | 5 | 11 |
| Microsoft Azure VNet | 5 | 11 |
| Google Cloud VPC | 4 | 12 |
| Oracle Cloud VCN | 3 | 13 |
Good to know
A /28 (14 usable hosts) splits a /24 into sixteen. A frequent pick for a small group of devices, a DMZ, or a load balancer pool.
How a /28 is calculated
- The /28 means the first 28 bits are the network portion, leaving 4 host bits.
- Total addresses = 2^(32 - 28) = 2^4 = 16.
- Usable hosts (standard) = 16 - 2 (network + broadcast) = 14.
- Subnet mask = 255.255.255.240; wildcard mask = 0.0.0.15.
Want to split a /28 into smaller subnets, see every address range, or plan a VLSM layout? Open the free subnet calculator →