Subnet for 30 hosts
A network that needs 30 hosts fits in a /27, mask 255.255.255.224, with 30 usable addresses.
A network built for exactly 30 hosts fits a /27 with no waste. The mask is 255.255.255.224, and all 30 of its usable addresses are spoken for.
Go one prefix smaller, to a /28, and the block only holds 14 usable addresses, not enough room for 30 hosts. A /27 is the smallest standard block that fits.
Enter any address below to see the exact network, broadcast, and host range for a /27 block.
Calculate a /27 network
Accepts CIDR (192.0.2.0/24), IP + mask (192.0.2.0 255.255.255.0), or a bare IP (defaults to /24).
11000000.00000000.00000010.0000000011111111.11111111.11111111.11100000Example: 192.0.2.0/27
Taking 192.0.2.0/27 as a worked example, a /27 block breaks down like this:
| Network address | 192.0.2.0 |
|---|---|
| Usable range | 192.0.2.1 - 192.0.2.30 |
| Broadcast address | 192.0.2.31 |
| Total addresses | 32 |
| Usable hosts | 30 |
Frequently asked questions
What subnet mask do I need for 30 hosts?
A network with 30 hosts fits in a /27, which uses the mask 255.255.255.224 and provides 30 usable addresses.
How many addresses does a /27 block have in total?
A /27 has 32 total addresses, 30 of them usable (the total minus the network and broadcast addresses, except for /31 and /32).
Is there a smaller subnet that still fits 30 hosts?
No. A /27 has exactly 30 usable addresses, which makes it the smallest standard block that fits 30 hosts without going over.
How do I work this out myself?
Find the smallest power of two, minus two, that is at least 30. That takes 5 host bits, which leaves a /27 prefix. See how to calculate a subnet mask for the full method.