Polypeptide Calculator

Paste an amino acid sequence to get its molecular weight, net charge at pH 7 and composition.

Inputs

Result

Formula used

Molecular weight (Da) = sum of average residue masses + 18.01528 (one water for the free termini)

Net charge at pH 7.0 = [N-terminus and K, R, H positive terms] + [C-terminus and D, E, C, Y negative terms], each from its pKa by the Henderson-Hasselbalch relation

Composition = count of each amino acid, and that count as a percentage of the sequence length