How to use this subnet calculator
Enter any IPv4 address with a CIDR prefix (e.g., 192.168.1.0/24)
or with a dotted-decimal subnet mask (e.g., 10.0.0.0 255.0.0.0).
The calculator instantly returns all subnet parameters.
Understanding CIDR notation
CIDR (Classless Inter-Domain Routing) notation combines the network address
with the prefix length using a slash. A /24 prefix means the first
24 bits are the network portion, leaving 8 bits for host addresses —
yielding 254 usable hosts.
Common subnet masks reference
| CIDR | Subnet mask | Usable hosts |
|---|---|---|
| /30 | 255.255.255.252 | 2 |
| /29 | 255.255.255.248 | 6 |
| /28 | 255.255.255.240 | 14 |
| /27 | 255.255.255.224 | 30 |
| /26 | 255.255.255.192 | 62 |
| /25 | 255.255.255.128 | 126 |
| /24 | 255.255.255.0 | 254 |
| /23 | 255.255.254.0 | 510 |
| /22 | 255.255.252.0 | 1022 |
| /16 | 255.255.0.0 | 65534 |
| /8 | 255.0.0.0 | 16777214 |