Subnet-Calculator

Subnet Calculator is a clean, professional networking tool for network engineers, sysadmins, CCNA/CCNP students and developers. Enter an IP address and a prefix (or CIDR) and instantly get every subnet detail you need. IPv4 CALCULATIONS • Network and broadcast addresses • Usable host range and host count • Subnet mask, wildcard (inverse) mask, hex mask • Address class (A/B/C/D/E) and category (private / public / loopback / link-local / multicast …) • Binary view with the network and host portions colour-coded • Convert freely between mask and CIDR prefix • Correct handling of /31 (point-to-point) and /32 (single host) IPv6 CALCULATIONS • Address compression (::) and full expansion • Address type detection (global unicast / link-local / unique local / multicast …) • Network prefix, first and last address • Total address count (shown as a power of two and exact value), number of /64 subnets SUBNETTING • Equal split: divide a network by a new prefix and list every subnet • VLSM: allocate the right-sized subnet for each host requirement automatically WHY YOU'LL LIKE IT • 100% offline — no network access, no data collected, full privacy • Tap any result to copy it • Dark mode, universal for iPhone and iPad • English & Chinese, follows your system language • Clean interface, no ads Whether you're planning a network, studying for a certification, or troubleshooting on the job, this tool gets your subnet math done fast and accurately.