/8 Subnet
16 million IPs — Class A network
A /8 block (also called a Class A network) contains 16,777,216 IP addresses. The entire 10.0.0.0/8 private range is a single /8. Very large organisations and ISPs hold /8 allocations from IANA.
Common Use Cases
- → Entire Class A private range (10.0.0.0/8)
- → Large ISP or carrier allocations
- → Enterprise-wide addressing plan
Example /8 Networks
| CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|
| 10.0.0.0/8 | 10.0.0.0 | 10.0.0.1 | 10.255.255.254 | 10.255.255.255 | 16,777,214 |
| 172.0.0.0/8 | 172.0.0.0 | 172.0.0.1 | 172.255.255.254 | 172.255.255.255 | 16,777,214 |
| 172.0.0.0/8 | 172.0.0.0 | 172.0.0.1 | 172.255.255.254 | 172.255.255.255 | 16,777,214 |
| 192.0.0.0/8 | 192.0.0.0 | 192.0.0.1 | 192.255.255.254 | 192.255.255.255 | 16,777,214 |
| 192.0.0.0/8 | 192.0.0.0 | 192.0.0.1 | 192.255.255.254 | 192.255.255.255 | 16,777,214 |
| 10.0.0.0/8 | 10.0.0.0 | 10.0.0.1 | 10.255.255.254 | 10.255.255.255 | 16,777,214 |
How /8 Compares
| Prefix | Total IPs | Usable Hosts | Subnet Mask | Typical Use |
|---|---|---|---|---|
| /5 | 134,217,728 | 134,217,726 | 248.0.0.0 | — |
| /6 | 67,108,864 | 67,108,862 | 252.0.0.0 | — |
| /7 | 33,554,432 | 33,554,430 | 254.0.0.0 | — |
| /8 ◀ | 16,777,216 | 16,777,214 | 255.0.0.0 | Entire private Class A or ISP allocation |
| /9 | 8,388,608 | 8,388,606 | 255.128.0.0 | Large regional allocations |
| /10 | 4,194,304 | 4,194,302 | 255.192.0.0 | Enterprise regional segment |
| /11 | 2,097,152 | 2,097,150 | 255.224.0.0 | — |
Frequently Asked Questions
How many IPs are in a /8?
A /8 subnet contains 16,777,216 total IP addresses and 16,777,214 usable host addresses. The network address (first IP) and broadcast address (last IP) are reserved and cannot be assigned to hosts.
What is the subnet mask for /8?
The subnet mask for a /8 is 255.0.0.0.
In CIDR notation, the prefix length /8 means
the first 8 bits of the address are the network portion.
The wildcard (inverse) mask is 0.255.255.255.
How many /8 subnets fit in a /7?
Exactly 2 — a /7 can be split into two /8 subnets of equal size.