Quick presets
How to use the CIDR Calculator
- Enter an IP address with its prefix length in CIDR notation (e.g.
192.168.1.0/24). - Click Calculate or use a quick preset.
- The tool shows the network address, broadcast, first and last host, subnet mask, wildcard, and host count.
CIDR notation explained
CIDR (Classless Inter-Domain Routing) represents an IP address range as a base address followed by a prefix length (/24). The prefix length indicates how many bits form the network part. The remaining bits define host addresses.
Usable hosts = 2^(32 − prefix) − 2 (the network and broadcast addresses cannot be assigned to hosts).
Common subnet sizes
| CIDR | Subnet mask | Total addresses | Usable hosts |
|---|---|---|---|
| /30 | 255.255.255.252 | 4 | 2 |
| /29 | 255.255.255.248 | 8 | 6 |
| /28 | 255.255.255.240 | 16 | 14 |
| /27 | 255.255.255.224 | 32 | 30 |
| /26 | 255.255.255.192 | 64 | 62 |
| /25 | 255.255.255.128 | 128 | 126 |
| /24 | 255.255.255.0 | 256 | 254 |
| /16 | 255.255.0.0 | 65,536 | 65,534 |
| /8 | 255.0.0.0 | 16,777,216 | 16,777,214 |
Private IP address ranges
10.0.0.0/8, Class A private range (large enterprises)172.16.0.0/12, Class B private range (medium networks)192.168.0.0/16, Class C private range (home and small office)