IP Subnet Calculator
Enter an IP address and CIDR prefix length to instantly see the network address, broadcast address, usable host range, and total number of hosts. Handy for network planning, firewall rules, and VLAN configuration.
Subnetting divides a larger network into smaller segments. The CIDR prefix (like /24) tells you how many bits are used for the network portion of the address.
How it works:
- Network address -- the first address in the subnet, identifies the network itself
- Broadcast address -- the last address, used to reach all hosts on the subnet
- Usable hosts -- every address between network and broadcast (total addresses minus 2)
- Wildcard mask -- the inverse of the subnet mask, used in ACLs and OSPF configs
Common subnets:
- /32 -- single host (1 address)
- /30 -- point-to-point link (2 usable hosts)
- /24 -- standard LAN (254 usable hosts)
- /16 -- large network (65,534 usable hosts)
- /8 -- class A (16,777,214 usable hosts)