IP Subnet Calculator
Enter an IPv4 address and CIDR prefix to instantly get the network address, broadcast address, subnet mask, and usable host range for network planning.
IP Address & CIDR
Result
Enter an IP and CIDR prefix to calculate subnet details
Disclaimer: This calculator supports IPv4 only. Always verify subnet plans against your network hardware and provider documentation before deploying to production infrastructure.
About the IP Subnet Calculator
Subnetting divides a larger IP network into smaller sub-networks, improving routing efficiency and network organization. This calculator takes an IPv4 address and CIDR prefix length and derives all the key subnet parameters.
Key Terms
The network address identifies the subnet itself (host bits all zero). The broadcast address targets all hosts on the subnet (host bits all one). The usable host range excludes both the network and broadcast addresses — these are the addresses you can actually assign to devices.
CIDR Notation
CIDR (Classless Inter-Domain Routing) notation like /24 specifies how many bits of the 32-bit IPv4 address are the network portion. A /24 means 24 network bits and 8 host bits, giving 256 total addresses (254 usable) — the classic "Class C" sized subnet.