/3 vs /5 — Subnet Comparison
A /3 subnet is 4× larger than a /5. Every additional bit in the prefix halves the address space — the 2-bit difference between these two means /3 has 22 = 4 times as many addresses.
Key Differences
How 4 /5 Subnets Divide a /3
Example using 10.0.0.0/3 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 0.0.0.0/5 | 0.0.0.0 | 0.0.0.1 | 7.255.255.254 | 7.255.255.255 | 134,217,726 |
| 2 | 8.0.0.0/5 | 8.0.0.0 | 8.0.0.1 | 15.255.255.254 | 15.255.255.255 | 134,217,726 |
| 3 | 16.0.0.0/5 | 16.0.0.0 | 16.0.0.1 | 23.255.255.254 | 23.255.255.255 | 134,217,726 |
| 4 | 24.0.0.0/5 | 24.0.0.0 | 24.0.0.1 | 31.255.255.254 | 31.255.255.255 | 134,217,726 |
FAQ
What is the difference between /3 and /5?
A /3 has 536,870,910 usable hosts
and a /5 has 134,217,726.
The subnet masks differ: /3 uses 224.0.0.0
while /5 uses 248.0.0.0.
Every additional bit in the prefix halves the number of addresses — so the 2-bit gap means
/3 is exactly 4× larger.
How many /5 subnets fit in a /3?
Exactly 4 /5 subnets fit perfectly inside one /3 with no wasted space. To split a /3 into /5s, 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.