/7 Subnet: Mask 254.0.0.0, 33,554,430 Usable Hosts
A /7 subnet has a subnet mask of 254.0.0.0 and contains 33,554,432 total IP addresses, of which 33,554,430 are usable host addresses (the network and broadcast addresses are reserved). A /7 contains 131,072 /24 networks.
| CIDR notation | /7 |
|---|---|
| Subnet mask | 254.0.0.0 |
| Wildcard mask | 1.255.255.255 |
| Mask in binary | 11111110.00000000.00000000.00000000 |
| Total addresses | 33,554,432 (2^25) |
| Usable hosts | 33,554,430 |
| Host bits | 25 |
Usable hosts in a /7 by platform
Cloud providers reserve more than the usual two addresses per subnet, so the same /7 gives you fewer usable IPs in the cloud than on a standard LAN.
| Platform | Reserved IPs | Usable hosts |
|---|---|---|
| Standard (network + broadcast) | 2 | 33,554,430 |
| AWS VPC | 5 | 33,554,427 |
| Microsoft Azure VNet | 5 | 33,554,427 |
| Google Cloud VPC | 4 | 33,554,428 |
| Oracle Cloud VCN | 3 | 33,554,429 |
Good to know
A /7 subnet has a 254.0.0.0 mask and 33,554,432 total addresses (33,554,430 usable). Each step from /7 to /8 halves the block; each step back to /6 doubles it.
How a /7 is calculated
- The /7 means the first 7 bits are the network portion, leaving 25 host bits.
- Total addresses = 2^(32 - 7) = 2^25 = 33,554,432.
- Usable hosts (standard) = 33,554,432 - 2 (network + broadcast) = 33,554,430.
- Subnet mask = 254.0.0.0; wildcard mask = 1.255.255.255.
Want to split a /7 into smaller subnets, see every address range, or plan a VLSM layout? Open the free subnet calculator →