Analysing your IQ
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Calculate your "mental age" using the classic Stern formula. Enter your IQ score and chronological age to see how your cognitive ability compares to age-based norms.
Mental age is a historical concept from early IQ testing (developed by Binet and Stern in the early 1900s). Modern psychologists no longer use mental age because it breaks down for adults and can be misleading. Contemporary IQ testing uses deviation scores and percentile-based comparisons, which are more statistically meaningful. This calculator is provided for educational and entertainment purposes only.
Formula
Mental Age = (IQ ÷ 100) × Chronological Age
The concept of mental age was introduced by Alfred Binet and Theodore Simon in 1905 as part of the first practical intelligence test. A child's mental age was determined by which age group's test items they could successfully complete.
In 1912, William Stern proposed the "intelligence quotient" (IQ) as the ratio of mental age to chronological age, multiplied by 100. A child with a mental age of 12 and a chronological age of 10 would have an IQ of (12/10) x 100 = 120.
This ratio IQ approach was eventually replaced by the "deviation IQ" introduced by David Wechsler in 1939. Deviation IQ compares an individual's test performance to the statistical distribution of scores for their age group, using a mean of 100 and standard deviation of 15.
The shift away from mental age occurred because the ratio approach produces misleading results for adults. Cognitive development plateaus in early adulthood, so the mental-age-to-chronological-age ratio becomes increasingly meaningless with age.
The classic mental age formula is: Mental Age = (IQ / 100) x Chronological Age. For example, a 30-year-old with an IQ of 120 would have a mental age of (120/100) x 30 = 36. This concept was originally developed by Alfred Binet and later refined by William Stern.
Mental age is a historical concept from early IQ testing that is no longer used in modern psychology. Contemporary psychologists prefer percentile-based comparisons and deviation IQ scores, which provide more statistically meaningful comparisons. Mental age can be misleading, especially for adults.
Psychologists moved away from mental age because it breaks down for adults. Cognitive ability does not scale linearly with age after adolescence. A 60-year-old with an IQ of 130 does not think like a 78-year-old. Modern deviation IQ scores compare individuals to age-matched peers, which is more statistically meaningful.
