Analyze protein sequences with residue molecular weight details. Get totals, exports, and example data instantly. Built for study, validation, and routine lab work tasks.
| Example Name | Sequence | Length | Average Mass (Da) | Monoisotopic Mass (Da) |
|---|---|---|---|---|
| Sample Peptide 1 | PEPTIDE | 7 | 673.7258 | 673.2860 |
| Sample Peptide 2 | ACDEFGHIK | 9 | 857.0026 | 856.3592 |
| Sample Peptide 3 | MKWVTFISLL | 10 | 1057.4131 | 1056.5884 |
Neutral molecular weight = Sum of amino acid masses − ((Number of residues − 1) × Water mass)
Total complex mass = Neutral molecular weight × Copies
Charged m/z = (Total complex mass + (z × Proton mass)) ÷ z
For average mass, the water term is 18.01528 Da. For monoisotopic mass, the water term is 18.01056 Da.
This approach reflects peptide bond formation. Each bond removes one water molecule from the total free amino acid mass sum.
This amino acid protein molecular weight calculator helps you estimate peptide and protein mass from a sequence. It reads single letter amino acid input. It removes spaces, line breaks, numbers, and FASTA headers. That makes cleanup simple. The tool then totals residue masses and corrects for water loss during peptide bond formation.
You can choose average or monoisotopic mass values. Average mass is useful for general chemistry work and classroom problems. Monoisotopic mass is useful for mass spectrometry checks. You can also set the charge state. That lets the page show neutral molecular weight or charged m/z values. A copy multiplier is included for repeated chains or multimers.
Protein molecular weight supports many lab and study tasks. You may need it for electrophoresis planning, peptide synthesis review, proteomics preparation, cloning reports, or sequence validation. A fast sequence based estimate reduces manual errors. It also helps compare expected mass with measured instrument values.
The calculator also returns residue count and amino acid composition. That information helps you inspect sequence makeup. You can quickly see whether a protein is glycine rich, acidic, basic, sulfur containing, or aromatic. Those patterns often matter during purification, digestion, and downstream analysis.
Use this page when reviewing a synthetic peptide, checking a recombinant construct, or preparing a lab worksheet. It also fits teaching use. Students can test how sequence length changes mass. They can compare average and monoisotopic values. They can also inspect how charge affects m/z output.
The export buttons make reporting easier. CSV works well for spreadsheets and lab notes. PDF is useful for sharing a clean summary. The example data table below shows realistic sequence inputs. The formula section explains the math in a clear way. The how to use steps keep the workflow easy for beginners and advanced users alike.
Because the page shows the cleaned sequence, it also helps catch input mistakes early. Unsupported letters are flagged before calculation. That protects result quality. In short, this tool combines chemistry logic, sequence inspection, and export features in one compact workflow.
It estimates protein or peptide molecular weight from a one letter amino acid sequence. It can also show charged m/z values, residue totals, and amino acid composition for the submitted chain.
Use average mass for general chemistry calculations and broad reporting. Use monoisotopic mass when comparing with high resolution mass spectrometry data or exact isotope based peptide calculations.
Yes. Header lines that start with the greater than symbol are ignored. Spaces, line breaks, and numbers are removed so you can paste common sequence formats easily.
Each peptide bond forms through a condensation reaction. That removes water between residues. The calculator applies that adjustment so the final chain mass matches peptide chemistry.
No. This version accepts standard one letter amino acid symbols and also supports U and O. Ambiguous or unsupported letters are flagged so the result stays reliable.
Charge state changes the displayed ion m/z value. The neutral molecular weight is still calculated first. The selected protonation state then converts that mass into a charged measurement.
Yes. Increase the copies field to multiply the calculated chain mass. This is useful for dimers, trimers, repeated peptide units, or quick assembly estimates.
You can export a CSV summary for spreadsheet work and generate a PDF report for sharing. Both exports include the main result details and amino acid composition table.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.