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IP Subnet / CIDR Calculator

Enter an IPv4 address plus a CIDR prefix or subnet mask to get the network address, broadcast address, usable host range, and more — instantly, no signup.

Calculate a subnet

You can also type it as 192.168.1.10/24

CIDR prefix (0–32) or dotted-decimal mask

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation writes an IP address together with the number of bits used for the network portion, e.g. 192.168.1.0/24. The /24 means the first 24 bits are the network prefix, leaving 8 bits (256 addresses) for hosts on that subnet — 254 of them usable once you subtract the network and broadcast addresses.