Enter the percentage of the major enantiomer and the percentage of the minor enantiomer into the calculator to determine the enantiomeric excess.

Enantiomeric Excess Formula

The following formula is used to calculate the enantiomeric excess of a solution. 

EE = Me - me
  • Where %EE is the percentage of enantiomeric excess
  • %Me is the molar percentage of major enantiomer
  • %me is the molar percentage of minor enantiomer

To calculate the enantiomeric excess, subtract the molar percentage of the minor enantiomer from the molar percentage of the major enantiomer.

Enantiomeric Excess Definition

Enantiomeric excess is defined as the difference between the percentage of the major and minor enantiomers in a solution.

Example Problem

How to calculate enantiomeric excess?

The first step in calculating the enantiomeric excess is to determine the molar percentage of the major enantiomer.

For this problem, the major enantiomer is found to have a molar percentage of 60%.

The next step in calculating the enantiomeric excess is to determine the molar percentage of the minor enantiomer.

In this example, the minor enantiomer molar percentage is found to be 40%.

Finally, using the formula %EE = %Me – %me we can find the enantiomer excess.

%EE = %Me – %me = 60 -40 = 20%.