Free Protein Molecular Weight Calculator
Estimate protein molecular weight from the number of amino acid residues using the average residue mass.
Estimated Molecular Weight
33,018 Da
Estimated Molecular Weight vs Number of Amino Acid Residues
Protein Molecular Weight Estimation
The molecular weight of a protein can be estimated from the number of amino acid residues using the average residue weight.
Formula
MW = N × 110 + 18
where N is the number of residues and 110 Da is the average amino acid residue weight (after peptide bond formation removes water). The +18 accounts for the water molecule completing the N-terminus and C-terminus. The actual average residue weight is 111.1 Da for a typical protein composition.
Example Calculation
A protein with 300 amino acid residues.
- 01MW = 300 × 110 + 18 = 33,018 Da
- 02MW = 33.0 kDa
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