Free tool · All tools
Protein molecular weight calculator
Paste a protein sequence in one-letter code and get its molecular weight, full amino-acid composition and GRAVY hydropathy score — the numbers you need for gels, expression work and construct design.
0 bases · Spaces, line numbers and FASTA headers are removed automatically.
Composition
Good to know
How the weight is calculated
The tool adds the average isotopic masses of the amino acids and subtracts one water molecule (18.015 Da) for each peptide bond, the standard average-mass estimate. X counts as an average residue. Post-translational modifications and disulfide bonds are not included.