/18 Subnet Mask (255.255.192.0)
| Prefix | /18 |
|---|---|
| Subnet mask | 255.255.192.0 |
| Wildcard mask | 0.0.63.255 |
| Binary mask | 11111111.11111111.11000000.00000000 |
| Total addresses | 16,384 |
| Usable hosts | 16,382 |
| Host bits | 14 |
| Subnets of /18 in a /16 | 4 |
e.g. 10.0.0.5/22 or 10.0.0.5 255.255.252.0
| Network address | 172.16.0.0 | |
|---|---|---|
| Broadcast address | 172.16.63.255 | |
| First usable host | 172.16.0.1 | |
| Last usable host | 172.16.63.254 | |
| Total addresses | 16,384 | |
| Usable hosts | 16,382 | |
| Subnet mask | 255.255.192.0 | |
| Wildcard mask | 0.0.63.255 | |
| CIDR notation | 172.16.0.0/18 | |
| IP class | Class B (legacy) | |
| Address type | Private (RFC 1918) | |
| IP address (binary) | 10101100.00010000.00000000.00000000 | |
| Subnet mask (binary) | 11111111.11111111.11000000.00000000 |
■ network bits ■ host bits
| Requested hosts | CIDR | First host | Last host | Broadcast | Usable hosts |
|---|
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What is a /18 subnet?
A /18 subnet uses the first 18 bits of an IPv4 address for the network and leaves 14 bits for hosts. Its subnet mask is 255.255.192.0, and it contains 2¹⁴ = 16,384 addresses, of which 16,382 can be assigned to devices. Typical use: A quarter of a /16; a common size for a large VPC or the pod range of a small Kubernetes cluster. Use the subnet calculator above to check any /18 network.
/18 subnet example
For 172.16.0.0/18: network address 172.16.0.0, usable hosts 172.16.0.1 – 172.16.63.254, broadcast address 172.16.63.255, wildcard mask 0.0.63.255.
/18 networks in 172.16.0.0/16
A /16 holds 4 /18 networks:
- 172.16.0.0/18
- 172.16.64.0/18
- 172.16.128.0/18
- 172.16.192.0/18
Frequently asked questions
How many usable IPs are in a /18?
16,382. The block has 16,384 addresses; the first is the network address and the last is the broadcast address.
What is the subnet mask for /18?
255.255.192.0, or 11111111.11111111.11000000.00000000 in binary.
How many /18 subnets are in a /16?
4 (2²), because a /18 uses 2 more network bits than a /16.
What is the difference between /18 and /17?
A /17 (255.255.128.0) is twice as large: 32,768 addresses and 32,766 usable hosts, spanning two consecutive /18 blocks such as 172.16.0.0–172.16.127.255.