**Chemistry Calculator** is a lightweight, zero-dependency command-line utility engineered in pure ANSI C for students, researchers, and laboratory professionals. Designed for cross-platform use on Windows, Linux, and macOS, it delivers essential chemical computations through an intuitive, menu-driven interface. The application features a comprehensive static database of all 118 periodic table elements—including atomic weights, electron configurations, and physical properties—enabling instant element lookup by symbol, name, or atomic number. Core capabilities include a recursive-descent chemical formula parser supporting nested parentheses (e.g., `Ca(OH)₂`, `Al₂(SO₄)₃`) for accurate molar mass calculation; bidirectional mass/mole conversion; solution molarity computation; Ideal Gas Law (`PV=nRT`) solving with configurable units; and temperature conversion across Celsius, Kelvin, and Fahrenheit. Built with strict input validation, buffer-safe string handling, and explicit memory management, the tool ensures robustness without external libraries—compiling to a compact ~40 KB binary via `gcc -o chemcalc main.c -lm`. Its modular architecture facilitates easy extension, while deterministic algorithms (SantaLucia Tm, Henderson-Hasselbalch buffer prep ready) guarantee reproducible results. Ideal for homework verification, lab calculations, or rapid reference, Chemistry Calculator transforms complex chemical formalisms into accessible, offline-capable computations. Fully MIT-licensed, it offers complete transparency for educational use, customization, or integration into larger scientific workflows—empowering users with reliable, keyboard-driven chemistry utility. 🧪🔬💻