Protein Molecular Weight Calculator
Calculate MW, extinction coefficient, and isoelectric point from amino acid sequence
Enter sequence in single-letter code. Supports FASTA format (headers will be ignored).
Enter a protein sequence above to calculate molecular weight, extinction coefficient, and isoelectric point.
Disclaimer: Calculations assume average isotopic masses and do not account for post-translational modifications, disulfide bonds, or prosthetic groups. Extinction coefficient is estimated by the Pace method (Trp/Tyr/Cys). Isoelectric point is an approximation. Always verify with mass spectrometry or SDS-PAGE.