/7 vs /8 — Subnet Comparison
A /7 subnet is 2× larger than a /8. Every additional bit in the prefix halves the address space — the 1-bit difference between these two means /7 has 21 = 2 times as many addresses.
16 million IPs — Class A network
Typical Uses
- →Entire Class A private range (10.0.0.0/8)
- →Large ISP or carrier allocations
- →Enterprise-wide addressing plan
Key Differences
How 2 /8 Subnets Divide a /7
Example using 10.0.0.0/7 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 10.0.0.0/8 | 10.0.0.0 | 10.0.0.1 | 10.255.255.254 | 10.255.255.255 | 16,777,214 |
| 2 | 11.0.0.0/8 | 11.0.0.0 | 11.0.0.1 | 11.255.255.254 | 11.255.255.255 | 16,777,214 |
FAQ
What is the difference between /7 and /8?
A /7 has 33,554,430 usable hosts
and a /8 has 16,777,214.
The subnet masks differ: /7 uses 254.0.0.0
while /8 uses 255.0.0.0.
Every additional bit in the prefix halves the number of addresses — so the 1-bit gap means
/7 is exactly 2× larger.
How many /8 subnets fit in a /7?
Exactly 2 /8 subnets fit perfectly inside one /7 with no wasted space. To split a /7 into /8s, just increment the last 1 bit of the network address for each new subnet.
Which should I choose?
Choose based on how many hosts you need. Use the hosts → prefix calculator on the homepage to find the right size for your requirements.