🌐 IP Subnet Calculator

How to use the IP Subnet Calculator

Enter an IP address (e.g. 192.168.1.50) and either select a CIDR prefix from the dropdown (e.g. /24) or type a subnet mask (e.g. 255.255.255.0). Click Calculate to see all subnet details.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation writes a network as an IP address followed by a slash and a number representing the prefix length — e.g. 192.168.1.0/24. The /24 means the first 24 bits are the network part, giving 256 addresses (254 usable hosts).

Network vs. Broadcast address

The first address in a subnet is the network address (all host bits zero). The last is the broadcast address (all host bits one). Usable host addresses are everything in between.

Common subnets

/8 — Class A, ~16M hosts. /16 — Class B, ~65K hosts. /24 — Class C, 254 hosts. /30 — Point-to-point link, 2 hosts. /32 — Single host.