/16 Subnet: Mask 255.255.0.0, 65,534 Usable Hosts
A /16 subnet has a subnet mask of 255.255.0.0 and contains 65,536 total IP addresses, of which 65,534 are usable host addresses (the network and broadcast addresses are reserved). A /16 contains 256 /24 networks.
| CIDR notation | /16 |
|---|---|
| Subnet mask | 255.255.0.0 |
| Wildcard mask | 0.0.255.255 |
| Mask in binary | 11111111.11111111.00000000.00000000 |
| Total addresses | 65,536 (2^16) |
| Usable hosts | 65,534 |
| Host bits | 16 |
Usable hosts in a /16 by platform
Cloud providers reserve more than the usual two addresses per subnet, so the same /16 gives you fewer usable IPs in the cloud than on a standard LAN.
| Platform | Reserved IPs | Usable hosts |
|---|---|---|
| Standard (network + broadcast) | 2 | 65,534 |
| AWS VPC | 5 | 65,531 |
| Microsoft Azure VNet | 5 | 65,531 |
| Google Cloud VPC | 4 | 65,532 |
| Oracle Cloud VCN | 3 | 65,533 |
Good to know
A /16 is a former "Class B" network with 65,536 addresses. The 192.168.0.0/16 private range is a /16; many cloud VPCs default to a /16 so there is room to carve out dozens of subnets.
How a /16 is calculated
- The /16 means the first 16 bits are the network portion, leaving 16 host bits.
- Total addresses = 2^(32 - 16) = 2^16 = 65,536.
- Usable hosts (standard) = 65,536 - 2 (network + broadcast) = 65,534.
- Subnet mask = 255.255.0.0; wildcard mask = 0.0.255.255.
Want to split a /16 into smaller subnets, see every address range, or plan a VLSM layout? Open the free subnet calculator →