text: Since the MCAT is a pre req to med school, and med schools would require a transcript from an undergrad program, the average age of an MCAT taker would be around 20 years old.  However, if you are a genius of any sort and have completed the requirements ahead of the rest of the applicants the age at which you were to apply would be different.  Make sure you have done all the pre-work before even considering it.  Otherwise you will have to take it multiple times... not good!