Protein Molecular Weight Calculator
Calculate molecular weight of protein from amino acid composition
About this calculator
The Protein Molecular Weight Calculator determines the exact molecular weight of proteins based on their amino acid composition. This tool is essential for biochemists, researchers, and students working with protein analysis, purification, and characterization. By inputting the number of each amino acid residue in your protein sequence, you get precise molecular weight calculations needed for mass spectrometry analysis, protein quantification, gel electrophoresis interpretation, and experimental planning in proteomics research.
How to use
Enter the count of each of the 20 standard amino acids present in your protein sequence into the corresponding input fields. Leave fields blank or enter zero for amino acids not present in your protein. Click calculate to get the total molecular weight, which accounts for the standard atomic weights of all amino acid residues and peptide bond formation.
Frequently asked questions
What units does the calculator use for molecular weight?
The calculator provides results in Daltons (Da), the standard unit for molecular weight in biochemistry and mass spectrometry applications.
Does this calculator account for post-translational modifications?
No, this calculator only considers the 20 standard amino acids. Post-translational modifications like phosphorylation or glycosylation must be calculated separately.
How accurate are the molecular weight calculations?
The calculations use standard IUPAC atomic weights and are highly accurate for theoretical molecular weights of unmodified proteins.