How can one calculate the pi value of amino acids?

To calculate the pI (isoelectric point) value of amino acids, you can use their pKa values. The pI is the pH at which an amino acid carries no net charge. For amino acids with a basic side chain, the pI is the average of the pKa values of the amino and carboxyl groups. For amino acids with an acidic side chain, the pI is the average of the pKa values of the carboxyl and side chain groups.