How is IQ calculated?

The calculation of IQ, or Intelligence Quotient, is based on the formula that involves mental age and chronological age. The correct method of calculating IQ is to take the mental age achieved by an individual and divide it by their chronological age. This result is then multiplied by 100 to create a standardized score. This approach allows for a comparative measurement of intelligence across different ages, as it normalizes the score regardless of the age of the individual being tested.

The importance of this formula lies in its historical usage, particularly during the early development of intelligence testing, where intellectual capacity was characterized in relation to age-appropriate milestones. A score of 100 is considered average, allowing for a clear benchmark against which deviations in performance can be measured.