About the Protein Molecular Weight Calculator
A free tool for estimating protein molecular weight from an amino acid sequence.
What it is
This calculator sums the average residue mass of each amino acid in a single-letter sequence, then adds one water molecule for the free termini, to estimate the total molecular weight of the folded or unfolded polypeptide chain.
Features
All 20 amino acids
Standard single-letter codes with average residue masses.
Da and kDa
Results shown in both daltons and kilodaltons.
Residue stats
See residue count and average residue mass too.
Instant, private
Runs entirely in your browser. No data is sent anywhere.