/4 Subnet: Mask 240.0.0.0, 268,435,454 Usable Hosts
A /4 subnet has a subnet mask of 240.0.0.0 and contains 268,435,456 total IP addresses, of which 268,435,454 are usable host addresses (the network and broadcast addresses are reserved). A /4 contains 1,048,576 /24 networks.
| CIDR notation | /4 |
|---|---|
| Subnet mask | 240.0.0.0 |
| Wildcard mask | 15.255.255.255 |
| Mask in binary | 11110000.00000000.00000000.00000000 |
| Total addresses | 268,435,456 (2^28) |
| Usable hosts | 268,435,454 |
| Host bits | 28 |
Usable hosts in a /4 by platform
Cloud providers reserve more than the usual two addresses per subnet, so the same /4 gives you fewer usable IPs in the cloud than on a standard LAN.
| Platform | Reserved IPs | Usable hosts |
|---|---|---|
| Standard (network + broadcast) | 2 | 268,435,454 |
| AWS VPC | 5 | 268,435,451 |
| Microsoft Azure VNet | 5 | 268,435,451 |
| Google Cloud VPC | 4 | 268,435,452 |
| Oracle Cloud VCN | 3 | 268,435,453 |
Good to know
A /4 is the size of the IPv4 multicast block (224.0.0.0/4) and the reserved future-use block (240.0.0.0/4).
How a /4 is calculated
- The /4 means the first 4 bits are the network portion, leaving 28 host bits.
- Total addresses = 2^(32 - 4) = 2^28 = 268,435,456.
- Usable hosts (standard) = 268,435,456 - 2 (network + broadcast) = 268,435,454.
- Subnet mask = 240.0.0.0; wildcard mask = 15.255.255.255.
Want to split a /4 into smaller subnets, see every address range, or plan a VLSM layout? Open the free subnet calculator →