/18 Subnet: Mask 255.255.192.0, 16,382 Usable Hosts
A /18 subnet has a subnet mask of 255.255.192.0 and contains 16,384 total IP addresses, of which 16,382 are usable host addresses (the network and broadcast addresses are reserved). A /18 contains 64 /24 networks.
| CIDR notation | /18 |
|---|---|
| Subnet mask | 255.255.192.0 |
| Wildcard mask | 0.0.63.255 |
| Mask in binary | 11111111.11111111.11000000.00000000 |
| Total addresses | 16,384 (2^14) |
| Usable hosts | 16,382 |
| Host bits | 14 |
Usable hosts in a /18 by platform
Cloud providers reserve more than the usual two addresses per subnet, so the same /18 gives you fewer usable IPs in the cloud than on a standard LAN.
| Platform | Reserved IPs | Usable hosts |
|---|---|---|
| Standard (network + broadcast) | 2 | 16,382 |
| AWS VPC | 5 | 16,379 |
| Microsoft Azure VNet | 5 | 16,379 |
| Google Cloud VPC | 4 | 16,380 |
| Oracle Cloud VCN | 3 | 16,381 |
Good to know
A /18 subnet has a 255.255.192.0 mask and 16,384 total addresses (16,382 usable). Each step from /18 to /19 halves the block; each step back to /17 doubles it.
How a /18 is calculated
- The /18 means the first 18 bits are the network portion, leaving 14 host bits.
- Total addresses = 2^(32 - 18) = 2^14 = 16,384.
- Usable hosts (standard) = 16,384 - 2 (network + broadcast) = 16,382.
- Subnet mask = 255.255.192.0; wildcard mask = 0.0.63.255.
Want to split a /18 into smaller subnets, see every address range, or plan a VLSM layout? Open the free subnet calculator →