IPv4 and IPv6 subnet calculator

Enter an IP address with a CIDR prefix, IPv4 subnet mask, or wildcard mask and get an exact network calculation.

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The calculator supports RFC-aware IPv4 /31 and /32 behavior, IPv6 /127 and /128, canonical IPv6 formatting, reverse DNS names, and IANA special-purpose address classification. All calculations stay on your device and remain available offline.