/5 vs /6 — Subnet Comparison
A /5 subnet is 2× larger than a /6. Every additional bit in the prefix halves the address space — the 1-bit difference between these two means /5 has 21 = 2 times as many addresses.
Key Differences
How 2 /6 Subnets Divide a /5
Example using 10.0.0.0/5 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 8.0.0.0/6 | 8.0.0.0 | 8.0.0.1 | 11.255.255.254 | 11.255.255.255 | 67,108,862 |
| 2 | 12.0.0.0/6 | 12.0.0.0 | 12.0.0.1 | 15.255.255.254 | 15.255.255.255 | 67,108,862 |
FAQ
What is the difference between /5 and /6?
A /5 has 134,217,726 usable hosts
and a /6 has 67,108,862.
The subnet masks differ: /5 uses 248.0.0.0
while /6 uses 252.0.0.0.
Every additional bit in the prefix halves the number of addresses — so the 1-bit gap means
/5 is exactly 2× larger.
How many /6 subnets fit in a /5?
Exactly 2 /6 subnets fit perfectly inside one /5 with no wasted space. To split a /5 into /6s, 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.