NETWORK TOOL
Subnet Calculator
Calculate IP ranges and subnet details from CIDR notation.
About subnetting
What does /24 mean?
The number after the slash is how many bits of the address identify the network. A /24 leaves 8 bits for hosts, giving 256 addresses (254 usable).
Why are two addresses unusable?
The first address identifies the network itself and the last is the broadcast address. /31 and /32 are special cases used for point-to-point links and single hosts.
What is a wildcard mask?
It's the inverse of the subnet mask, used in router access lists and OSPF configuration.