From the developer: "Molecular Weight Calculator lets you calculate the molecular weight and percent composition of up to 20 compounds simultaneously. Features include a Mole/Mass Converter, a Formula Finder, Amino Acid Notation converter, Peptide Sequence Fragmentation Modelling with spectral plotting, and the ability to recognize isotopes and user-defined abbreviations. The calculator also includes abbreviation expansion, empirical formula conversion, and a built-in mathematical calculator. All formulas and settings are saved between uses. Includes support for International languages (Spanish, German, Portuguese, Russian, and English)."