🌐IP Subnet Calculator
e.g. 192.168.1.0
/8 to /32
An IP subnet calculator breaks an IP address space into smaller networks. CIDR (Classless Inter-Domain Routing) notation specifies how many bits belong to the network portion — /24 means 24 bits for network, 8 bits for hosts, allowing 254 usable host addresses. Subnetting is essential for network design, router configuration, and firewall rules.
- 1IP addresses are 32-bit numbers (IPv4), written as 4 octets: e.g. 192.168.1.0
- 2CIDR /n means first n bits are the network address
- 3Subnet mask = n ones followed by (32−n) zeros in binary
- 4Network address = IP AND subnet mask
- 5Broadcast address = network address OR NOT(subnet mask)
- 6Usable hosts = 2^(32−n) − 2 (subtract network and broadcast addresses)
192.168.1.0/24=Network: 192.168.1.0, Broadcast: 192.168.1.255, Hosts: 254/24 gives 256 addresses, 254 usable
10.0.0.0/8=Network: 10.0.0.0, Hosts: 16,777,214Class A private range — 16 million hosts
| CIDR | Subnet Mask | Usable Hosts | Typical Use |
|---|---|---|---|
| /30 | 255.255.255.252 | 2 | Point-to-point links |
| /29 | 255.255.255.248 | 6 | Small office |
| /28 | 255.255.255.240 | 14 | Small network |
| /27 | 255.255.255.224 | 30 | |
| /24 | 255.255.255.0 | 254 | Standard LAN |
| /16 | 255.255.0.0 | 65,534 | Large campus |
| /8 | 255.0.0.0 | 16,777,214 | ISP / Class A |
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