IP Calculator: Subnet Tool

IP Calculator is a fast, no-nonsense IPv4 subnet calculator built for network engineers, sysadmins, IT support and students. Type an address and every result updates instantly, as you type. No Calculate button, no waiting. FREE, PRIVATE, NO ADS • Completely free: no subscriptions, no in-app purchases • No ads, ever • No tracking, no analytics, no accounts, no data collected • Works fully offline: every calculation runs on your device LIVE SUBNET CALCULATOR • Enter an address on its own, or with a prefix or mask: 10.0.0.1/8 or 10.0.0.1 255.0.0.0 • Set the prefix with the +/– buttons, pick from every mask from /0 to /32, or drag across the 32-bit bar • See the network and host bits of your address light up as you change the prefix • Quick presets for common networks: /24, /16, /8, /30 WAN links, /31 point-to-point, CGNAT and more EVERY ANSWER AT A GLANCE • Network, broadcast, first and last usable host, and typical gateway • Usable hosts and total addresses, with correct handling of /31 and /32 • Where your address sits: "host 73 of 4,094", or whether it's the network or broadcast address • Subnet mask, wildcard mask and CIDR notation • Address class (A–E) and how the prefix relates to the classful network KNOWS EVERY SPECIAL RANGE Instantly identifies private (RFC 1918), public, loopback, link-local (APIPA), multicast, CGNAT (RFC 6598), documentation, benchmarking and reserved addresses, with the RFC for each. SPLIT SUBNETS Divide any network into smaller subnets and browse the full list with each subnet's host range. Tap any subnet to copy it. RANGE TO CIDR Turn any start–end address range into the smallest set of CIDR blocks that covers it exactly. Copy them all in one tap, and check whether any address falls inside the range. BINARY & FORMATS • Address and mask in binary, with network bits highlighted • Hex, decimal, IPv4-mapped IPv6 and reverse DNS (in-addr.arpa) POCKET REFERENCE • Address classes with ranges, leading bits and default masks • Every IANA special-purpose IPv4 range • A full CIDR cheat sheet from /32 to /0 with masks and host counts BUILT FOR DAILY USE • Tap any value to copy it, or share a full summary of a subnet • Remembers your last address • Designed for iPhone and iPad, with VoiceOver support Simple, accurate, and out of your way: the subnet tool you'll keep on your home screen.