Protein Molecular Weight Calculator
From Amino Acid Count
Estimate MW from number of amino acid residues
From Gene/CDS Length
Estimate protein MW from coding sequence length in base pairs
Formula
MW ≈ (Number of residues × Average residue MW) + 18.02 Da. Average residue MW ≈ 110 Da. Gene length (bp) ÷ 3 = number of amino acids.
Frequently Asked Questions
How do you estimate protein molecular weight?
Multiply the number of amino acid residues by the average residue molecular weight (~110 Da, which accounts for the loss of water during peptide bond formation) and add 18 Da for the terminal water molecule. A more precise calculation uses the specific weight of each amino acid.
What is the average molecular weight of an amino acid?
The average molecular weight of an amino acid residue in a protein is approximately 110 Da (or 128 Da for the free amino acid before peptide bond formation). The exact value depends on the amino acid composition.
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