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Calcimator

Protein Molecular Weight

Estimate protein molecular weight from amino acid count and post-translational modifications.

Inputs

Results

Total Molecular Weight

33,018 Da

Total Molecular Weight

33.02 kDa

Base Molecular Weight33,018 Da
Modification Mass0 Da
Est. Extinction Coeff (280nm)36,000 M⁻¹cm⁻¹
Codons Required300
mRNA Nucleotides900
How to Use This Calculator
  1. Enter Amino Acid Count and Post-Translational Modifications.
  2. Review Total Molecular Weight (Da) and Total Molecular Weight (kDa).
  3. Use Base Molecular Weight (Da) and Modification Mass (Da) to inform your decision.
  4. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Amino Acid Count

Amino Acid CountTotal Molecular WeightTotal Molecular Weight
5,001550,128 Da550.13 kDa
17,5011,925,128 Da1,925.13 kDa
32,5003,575,018 Da3,575.02 kDa
45,0004,950,018 Da4,950.02 kDa

What each input means

Amino Acid Count
Total number of amino acid residues in the protein. Average MW per residue is ~110 Da.
Post-Translational Modifications
Number of modifications (glycosylation, phosphorylation, etc.). Each adds ~100 Da on average.

How this is calculated

Formula

MW = (amino acids × 110 Da) + 18 + (modifications × 100 Da)

Worked example, using the default values

  1. Identify Input Parameters
    Amino Acid Count = 300, Post-Translational Modifications = 0 = 2 input(s) provided
  2. Calculate Total Molecular Weight
    Total Molecular Weight
    33018 = 33018
  3. Calculate Total Molecular Weight
    Total Molecular Weight
    33.02 = 33.02
  4. Calculate Base Molecular Weight
    Base Molecular Weight
    33018 = 33018
  5. Calculate Modification Mass
    Modification Mass = modifications * modificationMw
    0 = 0

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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