The Molecular Mass & Isotopic m/z Simulator is a professional, mass-spectrometry–ready calculation tool designed for chemists, analytical scientists, and advanced students. By entering a molecular formula, users can instantly calculate the monoisotopic (exact) mass, average molecular weight, and theoretical m/z values for common mass spectrometry ionization scenarios, including selectable adducts and charge states.

The simulator generates a theoretical isotopic pattern based on natural isotope abundances, displaying relative intensities (%) in both tabular form and an interactive bar-style spectrum, closely mirroring real HRMS data from LC-MS, Q-TOF, or Orbitrap instruments. In addition, it provides a full elemental analysis, reporting percent composition by mass for each element using standard atomic weights—ideal for stoichiometric checks, reporting, and teaching.

Built for accuracy, clarity, and education, this simulator bridges fundamental chemical concepts (molecular weight and elemental composition) with applied mass spectrometry interpretation (exact mass, isotopic envelopes, and m/z), making it a powerful tool for method development, data validation, and classroom instruction.