IQ COMPARISON TOOL
Compare two IQ scores side by side. See the difference in standard deviations, percentile gap, rarity comparison, and how both scores look on the bell curve.
Enter Two IQ Scores
Understanding IQ Differences
IQ score differences are best understood in terms of standard deviations (SD). On the Wechsler scale, one SD equals 15 IQ points. A difference of 1 SD is considered meaningful, while differences less than 0.5 SD (about 7 points) may fall within the margin of error of most IQ tests.
Due to the bell curve distribution, IQ differences have a much larger impact on percentile rankings at the extremes than near the average. The difference between IQ 100 and 110 is about 16 percentile points, while the difference between IQ 130 and 140 is only about 1.4 percentile points.
It is important to remember that IQ is just one measure of cognitive ability. Two people with different IQ scores may have very different cognitive profiles, with varying strengths in verbal reasoning, spatial ability, processing speed, and working memory.
Frequently Asked Questions
What does a 15-point IQ difference mean?
A 15-point IQ difference equals exactly one standard deviation. This means the higher scorer outperforms roughly 84% of people at the lower score's level. In practical terms, a 15-point gap is noticeable but not dramatic -- both individuals can succeed in most of the same fields.
Is a 10-point IQ difference significant?
A 10-point IQ difference represents about two-thirds of a standard deviation. While statistically meaningful, this gap is often within the margin of error of most IQ tests. Day-to-day cognitive differences between two people with a 10-point gap may be minimal.
Can two people with different IQs be equally successful?
Yes. IQ is just one factor in success. Motivation, emotional intelligence, creativity, work ethic, social skills, and opportunity all play major roles. Many highly successful people have average IQ scores, while some high-IQ individuals struggle professionally. IQ differences matter more at extreme levels.
