CIDR Calculator

Calculate network address, broadcast address, host range and usable IPs from a CIDR block.

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Frequently asked questions

What is CIDR?
CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses. A CIDR block is written as an IP address followed by a / and the prefix length (e.g. 192.168.1.0/24), where the prefix length indicates how many bits are the network portion.