A /27 subnet mask is 255.255.255.224, with 32 addresses and 30 usable hosts.
| CIDR prefix | /27 |
|---|---|
| Subnet mask | 255.255.255.224 |
| Subnet mask (binary) | 11111111.11111111.11111111.11100000 |
| Wildcard mask | 0.0.0.31 |
| Network bits / host bits | 27 / 5 |
| Total addresses | 32 |
| Usable hosts | 30 |
| /27 subnets in a /8 | 524,288 |
| /27 subnets in a /16 | 2,048 |
| /27 subnets in a /24 | 8 |
The mask ends 3 bits into octet 4, so blocks step in increments of 32 in that octet. An eighth of a /24: eight subnets of 30 usable hosts, a typical size for a small office or a server VLAN.
| Network | First usable host | Last usable host | Broadcast |
|---|---|---|---|
| 192.168.1.0/27 | 192.168.1.1 | 192.168.1.30 | 192.168.1.31 |
| 192.168.1.32/27 | 192.168.1.33 | 192.168.1.62 | 192.168.1.63 |
| 192.168.1.64/27 | 192.168.1.65 | 192.168.1.94 | 192.168.1.95 |
| 192.168.1.96/27 | 192.168.1.97 | 192.168.1.126 | 192.168.1.127 |
| 192.168.1.128/27 | 192.168.1.129 | 192.168.1.158 | 192.168.1.159 |
| 192.168.1.160/27 | 192.168.1.161 | 192.168.1.190 | 192.168.1.191 |
| 192.168.1.192/27 | 192.168.1.193 | 192.168.1.222 | 192.168.1.223 |
| 192.168.1.224/27 | 192.168.1.225 | 192.168.1.254 | 192.168.1.255 |
A /27 subnet mask is 255.255.255.224. In binary that is 11111111.11111111.11111111.11100000: 27 network bits followed by 5 host bits. The wildcard mask is 0.0.0.31.
A /27 holds 32 addresses in total. Subtracting the network and broadcast addresses leaves 30 usable hosts.
A /24 divides into 8 subnets of size /27, because each extra mask bit doubles the number of subnets.
Calculate this over HTTP: curl https://networkcalc.com/api/ip/192.168.1.0/27.
See the Subnet Calculator API.