/15 Subnet: Mask 255.254.0.0, 131,070 Usable Hosts
A /15 subnet has a subnet mask of 255.254.0.0 and contains 131,072 total IP addresses, of which 131,070 are usable host addresses (the network and broadcast addresses are reserved). A /15 contains 512 /24 networks.
| CIDR notation | /15 |
|---|---|
| Subnet mask | 255.254.0.0 |
| Wildcard mask | 0.1.255.255 |
| Mask in binary | 11111111.11111110.00000000.00000000 |
| Total addresses | 131,072 (2^17) |
| Usable hosts | 131,070 |
| Host bits | 17 |
Usable hosts in a /15 by platform
Cloud providers reserve more than the usual two addresses per subnet, so the same /15 gives you fewer usable IPs in the cloud than on a standard LAN.
| Platform | Reserved IPs | Usable hosts |
|---|---|---|
| Standard (network + broadcast) | 2 | 131,070 |
| AWS VPC | 5 | 131,067 |
| Microsoft Azure VNet | 5 | 131,067 |
| Google Cloud VPC | 4 | 131,068 |
| Oracle Cloud VCN | 3 | 131,069 |
Good to know
A /15 subnet has a 255.254.0.0 mask and 131,072 total addresses (131,070 usable). Each step from /15 to /16 halves the block; each step back to /14 doubles it.
How a /15 is calculated
- The /15 means the first 15 bits are the network portion, leaving 17 host bits.
- Total addresses = 2^(32 - 15) = 2^17 = 131,072.
- Usable hosts (standard) = 131,072 - 2 (network + broadcast) = 131,070.
- Subnet mask = 255.254.0.0; wildcard mask = 0.1.255.255.
Want to split a /15 into smaller subnets, see every address range, or plan a VLSM layout? Open the free subnet calculator →