Protein Molecular Weight

Calculate the average molecular weight (Da and kDa) of a protein from its amino acid sequence.

Sequence Input

Amino Acid Sequence (1-Letter Code)

Only standard amino acid codes (A-Z) are used for calculation.

Amino Acid Composition

Calculation Results

Enter sequence to see results

Overview

The molecular weight of a protein is the sum of the average molecular weights of its amino acids plus the weight of one water molecule. This calculator uses residue weights (average MW minus H20) to compute the total mass.

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Pro Tips

Enter the sequence using single-letter abbreviations (e.g., 'M' for Methionine).
Non-amino acid characters will be automatically ignored.
The calculation accounts for the N-terminal and C-terminal additions (+18.015 Da).

Fun Facts

"Molecular weight is commonly expressed in Daltons (Da) or kiloDaltons (kDa)."
"1 Dalton is approximately the mass of one hydrogen atom."
"Standard average amino acid weight is roughly 110 Daltons."
"The largest known protein is Titin, with a molecular weight of approx 3,800,000 Da (3800 kDa)."
"Proteins fold into complex 3D shapes determined by this sequence of amino acids."
"The word 'protein' comes from the Greek 'proteios', meaning 'primary' or 'first rank'."

Formula: Weight = Sum(AA Weights) + 18.015 Da (Terminal H2O)

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