AAT Bioquest

What is the difference between EC50 and IC50?

Posted February 13, 2020


The concepts of EC50 and IC50, albeit similar, are not quite identical. While EC50 measures the concentration of a drug inducing its half-maximal effective response, IC50 represents the concentration of an inhibitor at which 50% of inhibition in its activity is achieved. A good way to remember the difference is using the acronym ‘I’ in IC50, which stands for inhibition, unlike ‘E’ in EC50, which refers to effective.


Additional resources

IC50 Calculator

EC50 Calculator