/5 vs /7 — Subnet Comparison
A /5 subnet is 4× larger than a /7. Every additional bit in the prefix halves the address space — the 2-bit difference between these two means /5 has 22 = 4 times as many addresses.
Key Differences
How 4 /7 Subnets Divide a /5
Example using 10.0.0.0/5 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 8.0.0.0/7 | 8.0.0.0 | 8.0.0.1 | 9.255.255.254 | 9.255.255.255 | 33,554,430 |
| 2 | 10.0.0.0/7 | 10.0.0.0 | 10.0.0.1 | 11.255.255.254 | 11.255.255.255 | 33,554,430 |
| 3 | 12.0.0.0/7 | 12.0.0.0 | 12.0.0.1 | 13.255.255.254 | 13.255.255.255 | 33,554,430 |
| 4 | 14.0.0.0/7 | 14.0.0.0 | 14.0.0.1 | 15.255.255.254 | 15.255.255.255 | 33,554,430 |
FAQ
What is the difference between /5 and /7?
A /5 has 134,217,726 usable hosts
and a /7 has 33,554,430.
The subnet masks differ: /5 uses 248.0.0.0
while /7 uses 254.0.0.0.
Every additional bit in the prefix halves the number of addresses — so the 2-bit gap means
/5 is exactly 4× larger.
How many /7 subnets fit in a /5?
Exactly 4 /7 subnets fit perfectly inside one /5 with no wasted space. To split a /5 into /7s, just increment the last 2 bits 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.