/30 Subnet Mask (255.255.255.252)
| Prefix | /30 |
|---|---|
| Subnet mask | 255.255.255.252 |
| Wildcard mask | 0.0.0.3 |
| Binary mask | 11111111.11111111.11111111.11111100 |
| Total addresses | 4 |
| Usable hosts | 2 |
| Host bits | 2 |
| Subnets of /30 in a /24 | 64 |
| Block size | 4 addresses (subnets start every 4 in the last octet) |
e.g. 10.0.0.5/22 or 10.0.0.5 255.255.252.0
| Network address | 192.168.1.0 | |
|---|---|---|
| Broadcast address | 192.168.1.3 | |
| First usable host | 192.168.1.1 | |
| Last usable host | 192.168.1.2 | |
| Total addresses | 4 | |
| Usable hosts | 2 | |
| Subnet mask | 255.255.255.252 | |
| Wildcard mask | 0.0.0.3 | |
| CIDR notation | 192.168.1.0/30 | |
| IP class | Class C (legacy) | |
| Address type | Private (RFC 1918) | |
| IP address (binary) | 11000000.10101000.00000001.00000000 | |
| Subnet mask (binary) | 11111111.11111111.11111111.11111100 |
■ network bits ■ host bits
| Requested hosts | CIDR | First host | Last host | Broadcast | Usable hosts |
|---|
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What is a /30 subnet?
A /30 subnet uses the first 30 bits of an IPv4 address for the network and leaves 2 bits for hosts. Its subnet mask is 255.255.255.252, and it contains 2² = 4 addresses, of which 2 can be assigned to devices. Typical use: Classic point-to-point link: 2 usable hosts. Use the subnet calculator above to check any /30 network.
/30 subnet example
For 192.168.1.0/30: network address 192.168.1.0, usable hosts 192.168.1.1 – 192.168.1.2, broadcast address 192.168.1.3, wildcard mask 0.0.0.3.
/30 networks in 192.168.1.0/24
A /24 holds 64 /30 networks:
- 192.168.1.0/30
- 192.168.1.4/30
- 192.168.1.8/30
- 192.168.1.12/30
- 192.168.1.16/30
- 192.168.1.20/30
- 192.168.1.24/30
- 192.168.1.28/30
- 192.168.1.32/30
- 192.168.1.36/30
- 192.168.1.40/30
- 192.168.1.44/30
- 192.168.1.48/30
- 192.168.1.52/30
- 192.168.1.56/30
- 192.168.1.60/30
- 192.168.1.252/30
Frequently asked questions
How many usable IPs are in a /30?
2. The block has 4 addresses; the first is the network address and the last is the broadcast address.
What is the subnet mask for /30?
255.255.255.252, or 11111111.11111111.11111111.11111100 in binary.
How many /30 subnets are in a /24?
64 (2⁶), because a /30 uses 6 more network bits than a /24.
What is the difference between /30 and /29?
A /29 (255.255.255.248) is twice as large: 8 addresses and 6 usable hosts, spanning two consecutive /30 blocks such as 192.168.1.0–192.168.1.7.