Key Takeaways
- The average IQ score is 100 on most IQ tests.
- About 68% of people score between 85 and 115, or one standard deviation from the mean.
- Scores below 70 may indicate a developmental disability, while scores above 130 may suggest giftedness.
The average IQ (or mean) on many tests is 100. This can vary a bit because test publishers may use different scoring systems in their IQ (intelligence quotient) tests.
The standard deviation is 15 points, which means that 68% of scores lie between 85 and 115. Scores above this range are considered above average, while scores below this range are considered below average. Most people score near the average range, which is designed to fit into a normal distribution curve (aka “bell curve.”)
A low IQ score is anything 70 and below. A low score and other indicators might suggest that a person has an intellectual disability. Anything over 140 is considered a genius IQ score. For context, while there is no evidence that he was ever tested, Albert Einstein had an estimated score of around 160.
What does IQ mean, exactly?
IQ tests measure mental ability and provide a score to show how a person’s results compare to others in their age group. IQ encompasses a range of mental abilities, including verbal reasoning, visual abilities, spatial awareness, processing speed, and pattern recognition.
How the Average IQ Is Calculated
Historically, IQ tests have been scored in one of two ways.
- Mental age method: In the first method, a person’s mental age was divided by chronological age and then multiplied by 100. This formula was used during the early development of IQ tests, particularly by Alfred Binet and Theodore Simon.
- Standard score method: The other methods involve comparing scores against the scores of others in the individual’s same age group. This is the method used in modern IQ tests, such as the Wechsler scales and Stanford-Binet intelligence scales.
In the standard score method, psychometricians utilize a process known as standardization to make comparing and interpreting the meaning of IQ scores possible. This process is accomplished by administering the test to a representative sample and using these scores to establish standards, usually referred to as norms, by which all individual scores can be compared.
Because the median score is 100, experts can quickly assess individual test scores against the median to determine where these scores fall on the normal distribution. This means 50% of the scores fall above the median and 50% fall below it.
In the case of IQ scores, both the mean and median scores are 100. Classification systems can vary from one publisher to the next, although many tend to follow a similar rating system.
For example, on the Wechsler Adult Intelligence Scale and the Stanford-Binet test, scores between 90 and 109 are considered average IQ scores. On these same tests, scores between 110 and 119 are considered high average IQ scores. Scores between 80 and 89 are classified as low average.
Ninety-five percent of scores fall within two standard deviations (between 70 and 130). Outliers beyond those points represent only a small portion of the population, which means that only a small percentage of people have a very low IQ (below 70) or a very high IQ (above 130).
So in most cases, if you receive an IQ score of around 100, then you have what is considered an average IQ. Don’t worry—you are in good company. Most people score within one standard deviation of this average.
How Average IQ Is Measured
Intelligence tests are designed to measure crystallized and fluid intelligence.
- Crystallized intelligence involves your knowledge and skills you have acquired throughout your life
- Fluid intelligence is your ability to reason, problem-solve, and make sense of abstract information
Fluid intelligence is considered independent of learning and tends to decline in later adulthood. On the other hand, crystallized intelligence is directly related to education and experience and tends to increase as people age.
IQ tests are administered by licensed psychologists. There are different kinds of intelligence tests, but many involve a series of subtests that are designed to measure things like:
- Mathematical abilities
- Language skills
- Memory
- Reasoning skills
- Information processing speed
- Verbal comprehension
- Perceptual organization
- Working memory
Scores on these subtests are then combined to form an overall IQ score.
It is important to note that while people often talk about average, low and genius IQs, there is no single, definitive IQ test.
Common IQ Tests
Many tests are in use today, and each type of test measures, scores, and interprets performance differently. A few of the most common IQ tests in use today include:
- The Wechsler Adult Intelligence Scale for Adults
- The Wechsler Intelligence Scale for Children
- The Stanford-Binet Intelligence Scales
- The Kaufman Assessment Battery for Children
- The Cognitive Assessment System
- The Differential Ability Scales
- The Woodcock-Johnson Tests of Cognitive Abilities
Limitations and Controversies
Although an IQ score can predict things such as academic success, experts caution that it is not necessarily a guarantee of life success. Sometimes people with very high IQs do not fare well in life, while those with average IQs may thrive.
It’s important to remember that IQ tests do not fully capture every aspect of human intelligence, and often ignore things like emotional intelligence, social skills, and creativity.
IQ tests have numerous limitations, and have long been a source of controversy. Ever since the inception of the very first tests of intelligence, both academics and armchair psychologists have debated differences in intelligence.
One important factor to also note is that overall, IQ scores have been rising worldwide, a phenomenon known as the Flynn effect. However, recent research suggests this effect may be slowing or even reversing, possibly attributable to environmental factors.
Race and IQ Scores
During the 1920s, the US Army utilized IQ testing on recruits and found that different populations showed group differences in average IQ scores. Such findings helped fuel the eugenics movement and those who supported racial segregation.
The 1994 book The Bell Curve rekindled the argument and controversy, as the book promoted the notion that racial group differences in average IQ scores were largely the result of genetics. Critics suggest that such group differences are more accurately a product of environmental variables.
Such arguments over race and IQ reflect the age-old nature versus nurture debate. Are certain traits, characteristics, and abilities more heavily influenced by genetics or by environmental causes? Those who believe that race is a determinant of IQ are taking the side of nature, suggesting that heritability is the primary determinant of IQ.
However, research has found that while genetics plays a role in determining intelligence, environmental factors also play an important role. Some factors linked to group differences in average IQ scores include:
- Education
- Health
- Nutrition
- Socioeconomic status
- Testing bias
- Minority status
In response, the American Psychological Association formed a special task force led by psychologist Ulric Neisser to investigate the book’s claims. The task force found no direct evidence to support genetic explanations for test score differences between Blacks and Whites. Instead, it stated that there are no known explanations for such differences.
Discrimination and systemic bias may also affect these differences, including educational and healthcare disparities. It is also important to consider biases that may be inherent in the tests themselves.
Nationality Differences in Average IQ Scores
Studies of cognitive ability suggest differences exist in IQ scores among different nations. Such studies remain limited, but some explorations of this topic have been conducted by creating estimates of average IQ for different nations. Such differences may be largely linked to environmental influences such as:
- Socioeconomic factors
- Literacy rates
- Educational rates
- Life expectancy
One study found that countries like Finland and East Asian countries had higher average IQ scores, which is believed to be attributable to factors like educational quality.
Sex Differences in Average IQ Scores
Over the years, some researchers have argued that either males or females held an advantage in terms of IQ while others have argued that there are no significant differences between men and women.
Research suggests that while there is no average difference in IQ scores between men and women, there tends to be more variability in IQ scores among men.
Research has found that there are slight differences in the performance of verbal and spatial tasks, with women performing better on some verbal tasks and men performing better on some spatial ability tasks. However, researchers believe that this disparity is only partially due to biological differences and is also influenced by culture, experiences, and education.
What Does It Mean to Have an Average IQ?
While some limited generalizations can be made in relation to your average IQ score, keep the following in mind:
- It means you have average reasoning and problem-solving skills. Your IQ score might be a good general indicator of your reasoning and problem-solving abilities, but many psychologists suggest that these tests don’t tell the whole story.
- An average IQ score might not tell the whole story about your capabilities. A few things they don’t measure are practical skills and talents. You might have an average IQ score, but you might also be a great musician, a creative artist, an incredible singer, or a mechanical whiz. Psychologist Howard Gardner developed a theory of multiple intelligences designed to address this perceived shortcoming in popular conceptions of IQ.
- IQ scores are not necessarily set in stone. Researchers have also found that they can change over time. Education has a positive effect on IQ scores during adolescence. Scores increase by approximately one to five points for every additional year of schooling.
- Some experts suggest that EQ might matter even more than IQ. IQ tests also fail to address things like how curious you are about the world around you and how good you are at understanding and managing emotions. Some experts, including writer Daniel Goleman, suggest that emotional intelligence (often referred to as EQ) might even be more important than IQ.
- High or average IQ doesn’t guarantee success: Researchers have found that while having a high IQ can indeed give people an edge in many areas of life, it is certainly no guarantee of life success.
Don’t stress out if you’re not a “genius.” The truth is, the vast majority of people aren’t geniuses either. Instead, most people are somewhere within a 15-point range of the average IQ score.
Just as having a high IQ doesn’t ensure success, having an average or low IQ doesn’t ensure failure or mediocrity. Even if you have what is considered a low IQ, you may be smart in many other ways and have many other talents and abilities that aren’t reflected on a single test. Other factors, such as hard work, resilience, perseverance, and overall attitude, are important pieces of the puzzle.
