Subnet Calculator
Calculate IP subnets – netmask, broadcast, host range and CIDR notation.
How the Subnet Calculator Works
Enter an IPv4 address with CIDR prefix (e.g. 192.168.1.0/24) and instantly get all relevant subnet information: network address, broadcast, subnet mask, wildcard mask, host range and usable host count. The calculator supports all prefixes from /0 to /32 and also shows the binary representation.
Subnet Calculator FAQ
What is a subnet?
A subnet is a logically separated section of an IP network. Subnetting divides a large network into smaller sub-networks to improve management, security and efficiency. Each subnet has its own network address, broadcast address and a defined host range.
What does CIDR notation (e.g. /24) mean?
CIDR (Classless Inter-Domain Routing) describes how many bits of the IP address are reserved for the network. A /24 network has 256 IP addresses (254 usable hosts), a /16 network has 65,536 addresses. The higher the number after the slash, the smaller the subnet.
What is the difference between subnet mask and wildcard mask?
The subnet mask (e.g. 255.255.255.0) marks the network portion of an IP address. The wildcard mask is the bitwise inverse (e.g. 0.0.0.255) and is mainly used in Cisco routers and access lists. Both describe the same subnet, just from different perspectives.
Why are not all IP addresses in a subnet usable?
Two addresses in every subnet are reserved: the first address is the network address (identifies the subnet) and the last is the broadcast address (sends to all hosts in the subnet). In a /24 network with 256 addresses, 254 remain usable for hosts.