/18 vs /22 — Subnet Comparison
A /18 subnet is 16× larger than a /22. Every additional bit in the prefix halves the address space — the 4-bit difference between these two means /18 has 24 = 16 times as many addresses.
16K IPs — quarter of a /16
Typical Uses
- →VPC tier segmentation
- →Large-office building network
1K IPs — medium site subnet
Typical Uses
- →Medium office floor VLAN
- →Application tier with ~500 hosts
- →Cloud subnet for a single microservice cluster
Key Differences
How 16 /22 Subnets Divide a /18
Example using 10.0.0.0/18 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 10.0.0.0/22 | 10.0.0.0 | 10.0.0.1 | 10.0.3.254 | 10.0.3.255 | 1,022 |
| 2 | 10.0.4.0/22 | 10.0.4.0 | 10.0.4.1 | 10.0.7.254 | 10.0.7.255 | 1,022 |
| 3 | 10.0.8.0/22 | 10.0.8.0 | 10.0.8.1 | 10.0.11.254 | 10.0.11.255 | 1,022 |
| 4 | 10.0.12.0/22 | 10.0.12.0 | 10.0.12.1 | 10.0.15.254 | 10.0.15.255 | 1,022 |
| 5 | 10.0.16.0/22 | 10.0.16.0 | 10.0.16.1 | 10.0.19.254 | 10.0.19.255 | 1,022 |
| 6 | 10.0.20.0/22 | 10.0.20.0 | 10.0.20.1 | 10.0.23.254 | 10.0.23.255 | 1,022 |
| 7 | 10.0.24.0/22 | 10.0.24.0 | 10.0.24.1 | 10.0.27.254 | 10.0.27.255 | 1,022 |
| 8 | 10.0.28.0/22 | 10.0.28.0 | 10.0.28.1 | 10.0.31.254 | 10.0.31.255 | 1,022 |
| 9 | 10.0.32.0/22 | 10.0.32.0 | 10.0.32.1 | 10.0.35.254 | 10.0.35.255 | 1,022 |
| 10 | 10.0.36.0/22 | 10.0.36.0 | 10.0.36.1 | 10.0.39.254 | 10.0.39.255 | 1,022 |
| 11 | 10.0.40.0/22 | 10.0.40.0 | 10.0.40.1 | 10.0.43.254 | 10.0.43.255 | 1,022 |
| 12 | 10.0.44.0/22 | 10.0.44.0 | 10.0.44.1 | 10.0.47.254 | 10.0.47.255 | 1,022 |
| 13 | 10.0.48.0/22 | 10.0.48.0 | 10.0.48.1 | 10.0.51.254 | 10.0.51.255 | 1,022 |
| 14 | 10.0.52.0/22 | 10.0.52.0 | 10.0.52.1 | 10.0.55.254 | 10.0.55.255 | 1,022 |
| 15 | 10.0.56.0/22 | 10.0.56.0 | 10.0.56.1 | 10.0.59.254 | 10.0.59.255 | 1,022 |
| 16 | 10.0.60.0/22 | 10.0.60.0 | 10.0.60.1 | 10.0.63.254 | 10.0.63.255 | 1,022 |
FAQ
What is the difference between /18 and /22?
A /18 has 16,382 usable hosts
and a /22 has 1,022.
The subnet masks differ: /18 uses 255.255.192.0
while /22 uses 255.255.252.0.
Every additional bit in the prefix halves the number of addresses — so the 4-bit gap means
/18 is exactly 16× larger.
How many /22 subnets fit in a /18?
Exactly 16 /22 subnets fit perfectly inside one /18 with no wasted space. To split a /18 into /22s, just increment the last 4 bits of the network address for each new subnet.
Which should I choose?
/18 is typically used for: VPC segment. /22 is better for: Medium office/application segment. Choose the smallest prefix that comfortably fits your host count — over-allocating wastes address space, but under-allocating means painful renumbering later.