/9 Subnet Mask (255.128.0.0)
| Prefix | /9 |
|---|---|
| Subnet mask | 255.128.0.0 |
| Wildcard mask | 0.127.255.255 |
| Binary mask | 11111111.10000000.00000000.00000000 |
| Total addresses | 8,388,608 |
| Usable hosts | 8,388,606 |
| Host bits | 23 |
| Subnets of /9 in a /8 | 2 |
e.g. 10.0.0.5/22 or 10.0.0.5 255.255.252.0
| Network address | 10.0.0.0 | |
|---|---|---|
| Broadcast address | 10.127.255.255 | |
| First usable host | 10.0.0.1 | |
| Last usable host | 10.127.255.254 | |
| Total addresses | 8,388,608 | |
| Usable hosts | 8,388,606 | |
| Subnet mask | 255.128.0.0 | |
| Wildcard mask | 0.127.255.255 | |
| CIDR notation | 10.0.0.0/9 | |
| IP class | Class A (legacy) | |
| Address type | Private (RFC 1918) | |
| IP address (binary) | 00001010.00000000.00000000.00000000 | |
| Subnet mask (binary) | 11111111.10000000.00000000.00000000 |
■ network bits ■ host bits
| Requested hosts | CIDR | First host | Last host | Broadcast | Usable hosts |
|---|
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What is a /9 subnet?
A /9 subnet uses the first 9 bits of an IPv4 address for the network and leaves 23 bits for hosts. Its subnet mask is 255.128.0.0, and it contains 2²³ = 8,388,608 addresses, of which 8,388,606 can be assigned to devices. Typical use: Half of a /8; used to split 10.0.0.0/8 into two large regions, such as 10.0.0.0/9 and 10.128.0.0/9. Use the subnet calculator above to check any /9 network.
/9 subnet example
For 10.0.0.0/9: network address 10.0.0.0, usable hosts 10.0.0.1 – 10.127.255.254, broadcast address 10.127.255.255, wildcard mask 0.127.255.255.
Frequently asked questions
How many usable IPs are in a /9?
8,388,606. The block has 8,388,608 addresses; the first is the network address and the last is the broadcast address.
What is the subnet mask for /9?
255.128.0.0, or 11111111.10000000.00000000.00000000 in binary.
How many /9 subnets are in a /8?
2 (2¹), because a /9 uses 1 more network bits than a /8.
What is the difference between /9 and /8?
A /8 (255.0.0.0) is twice as large: 16,777,216 addresses and 16,777,214 usable hosts, spanning two consecutive /9 blocks such as 10.0.0.0–10.255.255.255.