ChemCalc is a free online tool for mass spectrometry. Calculate molecular weight, monoisotopic mass, and isotopic distribution from a molecular formula. Find possible molecular formulas from a monoisotopic mass. Analyze peptide, nucleotide, and polymer fragmentation.
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Reference: Patiny L, Borel A. ChemCalc: a building block for tomorrow's chemical infrastructure. J Chem Inf Model. 2013. DOI: 10.1021/ci300563h
Enter a measured monoisotopic mass and element ranges to list every candidate molecular formula, filtered by ionization mode, ppm precision, and degree of unsaturation — for HRMS compound identification.