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CIDR Calculator
Type any IPv4 or IPv6 CIDR block. Get the network and broadcast addresses, the first and last usable host, the mask in dotted-decimal and binary, and the total address count. Pure bitwise arithmetic — no libraries, no API calls.
Accepts IPv4 (a.b.c.d/n) or IPv6 (x:x:x:x::/n).
Subnet
Binary mask visualisation
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