AAT Bioquest

Peptide and Protein Molecular Weight Calculator

The molecular weight (mw) of an oligopeptide or a protein can be determined by summation of the mw of its corresponding amino acid sequence. Certain modifications to this sequences can result in changes to the mw. This calculator provides the mw of an unmodified oligopeptide or protein.

The extinction coefficient of a oligopeptide or protein can also be calculated given its sequence. This value is useful for determining the concentration of a peptide or protein solution.

How to use this tool

1. Enter the amino acid sequence.

2. Press calculate to display the molecular weight.

Data Entry



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This online tool may be cited as follows


"Quest Calculate™ Peptide and Protein Molecular Weight Calculator." AAT Bioquest, Inc.9 Dec2023https://www.aatbio.com/tools/calculate-peptide-and-protein-molecular-weight-mw.


AAT Bioquest, Inc. (2023December 9). Quest Calculate™ Peptide and Protein Molecular Weight Calculator. AAT Bioquest. https://www.aatbio.com/tools/calculate-peptide-and-protein-molecular-weight-mw.

This online tool has been cited in 4 publications, including

Long-term imaging of individual mRNA molecules in living cells
Authors: Guo, Yue and Lee, Robin EC
Journal: Cell Reports Methods (2022): 100226
Deciphering $\beta$-tubulin gene of carbendazim resistant Fusarium solani isolate and its comparison with other Fusarium species
Authors: Tarafder, Mrinmay and Datta, Bejoysekhar
Journal: Current Genetics (2022): 1--19
Hemagglutination Inhibition (HAI) antibody landscapes after vaccination with H7Nx virus like particles
Authors: Jang, Hyesun and Ross, Ted M
Journal: PloS one (2021): e0246613
Frontiers in Molecular Pharming
Authors: Khan, Muhammad Sarwar
Journal: (2021)