Peptide Chemistry Tool
Molecular Weight Calculator
Enter any peptide sequence in single-letter amino acid code to calculate average and monoisotopic molecular weight. Includes amino acid composition breakdown and presets for common research peptides.
Calculation method: Sum of residue masses (peptide bond formation, −H₂O per bond) plus terminal H₂O. Average mass uses IUPAC atomic weights. Monoisotopic mass uses most-abundant isotope masses. Non-standard or modified residues are excluded from the calculation.
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Enter a sequence or load a preset above.