/28 vs /29 — Subnet Comparison
A /28 subnet is 2× larger than a /29. Every additional bit in the prefix halves the address space — the 1-bit difference between these two means /28 has 21 = 2 times as many addresses.
14 usable hosts — tiny segment
Typical Uses
- →AWS VPC endpoint subnet
- →NAT gateway dedicated subnet
- →Small server cluster
6 usable hosts — tiny cluster
Typical Uses
- →Small server cluster (web + app + db)
- →Infrastructure management segment
- →Very small office or branch
Key Differences
How 2 /29 Subnets Divide a /28
Example using 10.0.0.0/28 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 10.0.0.0/29 | 10.0.0.0 | 10.0.0.1 | 10.0.0.6 | 10.0.0.7 | 6 |
| 2 | 10.0.0.8/29 | 10.0.0.8 | 10.0.0.9 | 10.0.0.14 | 10.0.0.15 | 6 |
FAQ
What is the difference between /28 and /29?
A /28 has 14 usable hosts
and a /29 has 6.
The subnet masks differ: /28 uses 255.255.255.240
while /29 uses 255.255.255.248.
Every additional bit in the prefix halves the number of addresses — so the 1-bit gap means
/28 is exactly 2× larger.
How many /29 subnets fit in a /28?
Exactly 2 /29 subnets fit perfectly inside one /28 with no wasted space. To split a /28 into /29s, just increment the last 1 bit of the network address for each new subnet.
Which should I choose?
/28 is typically used for: AWS NAT/endpoint dedicated subnet. /29 is better for: Tiny server cluster or infra segment. Choose the smallest prefix that comfortably fits your host count — over-allocating wastes address space, but under-allocating means painful renumbering later.