CIDR / Subnet Calculator

Calculate subnet details from a CIDR notation (e.g. 192.168.1.0/24). Shows network address, broadcast address, first/last usable host, netmask, wildcard mask, and number of usable hosts.

CIDR Notation Reference

CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its associated network prefix length as a single value: address/prefix. The prefix is the number of bits in the network portion of the address. A /24 subnet has 8 host bits, giving 256 addresses (254 usable - network and broadcast addresses are reserved).

Common subnet sizes

/32 - single host (1 address)
/30 - point-to-point link (2 usable hosts)
/29 - 6 usable hosts
/28 - 14 usable hosts
/24 - 254 usable hosts (class C equivalent)
/16 - 65,534 usable hosts (class B equivalent)
/8 - 16,777,214 usable hosts (class A equivalent)

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