Calculate network details from an IP address and subnet mask (IPv4)
This IP subnet calculator helps network administrators and students quickly determine network addresses, broadcast addresses, usable host ranges, and host counts from an IPv4 address and subnet mask expressed in CIDR notation. It also identifies the IP class and displays the subnet mask in both decimal and binary formats.
CIDR (Classless Inter-Domain Routing) notation uses a forward slash followed by a number (e.g., /24) to indicate how many bits of the IP address represent the network portion. The remaining bits identify hosts. /24 means 24 network bits and 8 host bits, providing 254 usable addresses.
The first address in a subnet is the network address (identifies the subnet itself), and the last address is the broadcast address (used to send data to all hosts on the subnet). Neither can be assigned to a host interface, so they are subtracted from the total.