Enter a block in CIDR format (an IP address followed by a prefix, e.g. 192.168.1.0/24) to calculate its network address, broadcast address, subnet mask and the number of available hosts.

What is CIDR notation?

CIDR notation (e.g. 192.168.1.0/24) describes a block of IP addresses: the base address, followed by a slash and a prefix that indicates the size of the block. The larger the prefix, the smaller the block — a /24 contains 256 addresses, a /16 contains 65,536.

This notation makes it possible to calculate a block's network address, broadcast address, subnet mask and number of usable hosts, without having to do the binary math by hand.