logo
Products
Technologies
Applications
Services
Resources
Selection Guides
About
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.


Feedback
Have a question or a feature request about this tool? Feel free to reach out to us and let us know! We're always looking for ways to improve!

References
This online resource may be cited as follows
MLA
"Quest CalculatePeptide and Protein Molecular Weight Calculator." AAT Bioquest, Inc.7 Oct2025https://www.aatbio.com/tools/calculate-peptide-and-protein-molecular-weight-mw.
APA
AAT Bioquest, Inc. (2025October 7). Quest CalculatePeptide and Protein Molecular Weight Calculator. AAT Bioquest. https://www.aatbio.com/tools/calculate-peptide-and-protein-molecular-weight-mw.
BibTeXEndNoteRefMan
This online resource has been cited in 11 publications, including
SimPep and OP-AND: A deep learning framework and curated database for predicting osteogenic peptides
Authors: 
Ghobakhloo, Maryam and Ghorbanali, Zahra and Zare-Mirakabad, Fatemeh and Abbaszadeh, Roya and Taheri-Ledari, Mohammad and Zeynali, Bahman
Journal: 
PLOS Computational Biology (2025): e1013422
BitterDB: 2024 update on bitter ligands and taste receptors
Authors: 
Ziaikin, Evgenii and David, Moran and Uspenskaya, Sofya and Niv, Masha Y
Journal: 
Nucleic Acids Research (2024): gkae1044
Heterologous expression, characterization, and application of recombinant thermostable $\alpha$-amylase from Geobacillus sp. DS3 for porous starch production
Authors: 
Kurniawan, Dina Clarissa and Rohman, Muhammad Saifur and Witasari, Lucia Dhiantika
Journal: 
Biochemistry and Biophysics Reports (2024): 101784
Complexing Protein-Free Botulinum Neurotoxin A Formulations: Implications of Excipients for Immunogenicity
Authors: 
Martin, Michael Uwe and Frevert, Juergen and Tay, Clifton Ming
Journal: 
Toxins (2024): 101
Unveiling the Relationship between Ceftobiprole and High-Molecular-Mass (HMM) Penicillin-Binding Proteins (PBPs) in Enterococcus faecalis
Authors: 
Conti, Paola and Lazzaro, Lorenzo Mattia and Longo, Fabio and Lenzo, Federica and Giardina, Alessandra and Fortuna, Sebastiano Alberto and Stefani, Stefania and Campanile, Floriana
Journal: 
Antibiotics (2024): 65
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
Long-term imaging of individual mRNA molecules in living cells
Authors: 
Guo, Yue and Lee, Robin EC
Journal: 
Cell Reports Methods (2022): 100226
Frontiers in Molecular Pharming
Authors: 
Khan, Muhammad Sarwar
Hemagglutination Inhibition (HAI) antibody landscapes after vaccination with H7Nx virus like particles
Authors: 
Jang, Hyesun and Ross, Ted M
Journal: 
PloS one (2021): e0246613

  • Enter the amino acid sequence.
  • Press calculate to display the molecular weight.