VLSM Calculator

The VLSM Calculator computes subnet plans from a base IPv4 network and a list of host requirements. Users supply the base address and an array of host counts for each subnet; the tool determines the smallest CIDR prefix that satisfies each count and assigns consecutive address blocks. For every subnet it outputs the network address, the first and last usable addresses, the broadcast address, and the CIDR prefix.

How it works: subnets are ordered by descending host count, minimal prefixes are derived using 2^(32 - prefix) - 2 >= hosts, and blocks are allocated sequentially from the base address. The approach minimizes address waste and ensures non-overlapping ranges within the base network. It can process multiple subnets in a single run and flags overflow if all subnets do not fit.

Who benefits: network designers, IT admins, instructors, and students performing subnet planning exercises. The tool provides repeatable, auditable results suitable for formal designs and documentation. It also serves as a learning aid by demonstrating how host requirements translate to CIDR prefixes and subnet boundaries.

Core features include automatic prefix calculation, subnet metadata generation, optional multi-network input, and export-ready results in CSV or JSON formats.