OT Subnet Calculator

IP Subnet Calculator combines fast IPv4 calculations with professional network planning and a compact IPAM. Calculate network addresses, broadcasts, host ranges, subnet masks, and CIDR prefixes—or document complete sites, customers, and devices. FAST AND ACCURATE • Enter an IPv4 address or CIDR directly • Network, broadcast, first and last host • Usable host count and address classification • Quick selection for common prefixes • Copy and export results IPAM FOR YOUR NETWORKS • Folders and subfolders for sites, customers, or projects • Networks with CIDR, VLAN, location, status, and notes • Devices with hostname, IP, and MAC address • Complete CSV export • iCloud sync across your devices • Share your IPAM and collaborate with others PRO TOOLS • Overlap checks for conflicting networks • VLSM and VLAN planning • CIDR aggregation • IPv6 explorer and prefix comparison • Favorites, history, and folders LEARN AND UNDERSTAND Bit visualization, step-by-step guides, practical scenarios, interactive examples, a quiz, and a cheatsheet help both beginners and network professionals. Core calculators are free. IPAM, collaboration, and advanced tools are available permanently with Pro—no subscription.