/22 Subnet Mask ReferenceIPv4
Four /24s, 1,022 usable hosts, mask <code>255.255.252.0</code>: the /22 is arguably the best compromise between a cramped /24 and a sprawling /20. It is also the size registries have treated as the floor for fresh ISP allocations during the IPv4-scarcity era.
/22 facts at a glance
- Subnet mask
- 255.255.252.0
- Wildcard mask
- 0.0.3.255
- Binary mask
- 11111111.11111111.11111100.00000000
- Total addresses
- 1,024
- Usable hosts
- 1,022 (excludes network & broadcast)
- Block size
- 1,024 addresses (210)
- Typical role
- Mid-size networks and ISP allocations
Example /22 networks
Three consecutive /22 blocks, starting at the /22 boundary that contains 198.51.100.0:
| Network | Usable range | Usable hosts |
|---|---|---|
| 198.51.100.0/22 | 198.51.100.1 – 198.51.103.254 | 1,022 |
| 198.51.104.0/22 | 198.51.104.1 – 198.51.107.254 | 1,022 |
| 198.51.108.0/22 | 198.51.108.1 – 198.51.111.254 | 1,022 |
How to calculate a /22 mask
A /22 mask sets the first 22 bits of a 32-bit number to 1 and leaves the remaining 10 bits as 0. In binary that reads 11111111.11111111.11111100.00000000, which converts to dotted decimal 255.255.252.0. Each block covers a contiguous run of 210 = 1,024 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving 0.0.3.255.
Where /22 is used
- Mid-size branches or factories that want four VLAN-sized /24s under one allocation.
- Efficient cloud VPC sizing when a /16 would sit mostly idle.
- Public address blocks leased to customers who need more than one /24.
Alignment: the third octet advances in steps of four, so <code>10.1.4.0/22</code> spans 10.1.4.0 through 10.1.7.255.
Cloud-friendly: AWS accepts subnets from /16 down to /28, and a /22 stays comfortably inside every provider's bounds while wasting far less than a /16.
Frequently asked questions
How many usable hosts are in a /22?
1,022 of 1,024 total addresses.
What is the subnet mask for a /22?
<code>255.255.252.0</code>, wildcard <code>0.0.3.255</code>.
How many /24s are in a /22?
Four consecutive ones: for example, 10.1.4.0/22 holds the four /24 networks 10.1.4.0, 10.1.5.0, 10.1.6.0, and 10.1.7.0.
Why pick a /22 instead of a /24?
Headroom without extravagance: four LAN-sized segments under one summary line, with none of the idle sprawl of a /20 or /16.
Open this block in a calculator
Open the /22 block in the subnet calculator