Understanding IQ Scores: What Do They Really Mean?

Introduction to IQ Scores

Intelligence Quotient (IQ) scores are among the most widely recognized yet misunderstood measures in psychology. When you receive an IQ score, you're getting a numerical representation of your cognitive abilities relative to the general population. But what do these numbers actually mean, and how should you interpret them?

IQ scores are standardized to have a mean of 100 and a standard deviation of 15 points. This means that approximately 68% of the population scores between 85 and 115, while about 95% score between 70 and 130. Understanding this distribution is crucial for interpreting your own score accurately.

The Bell Curve and Normal Distribution

IQ scores follow what statisticians call a normal distribution or bell curve. This mathematical pattern means that most people cluster around the average (100), with fewer people scoring at the extremes. The standard deviation of 15 points means that:

About 68% of people score between 85-115 (within one standard deviation)
About 95% of people score between 70-130 (within two standard deviations)
About 99.7% of people score between 55-145 (within three standard deviations)

This distribution pattern was established through decades of psychological research and remains consistent across different populations and test types when properly standardized.

IQ Score Ranges Explained

IQ scores are typically categorized into ranges that help contextualize performance:

130 and Above: Very Superior

Scores of 130 and above represent approximately the top 2% of the population. Individuals in this range often demonstrate exceptional problem-solving abilities, rapid learning, and strong abstract reasoning. However, it's important to note that high IQ doesn't guarantee success in all areas of life, as factors like motivation, emotional intelligence, and practical skills also play crucial roles.

120-129: Superior

This range represents above-average cognitive abilities, typically placing individuals in the top 10% of the population. People in this range often excel academically and professionally, though individual achievement varies based on many factors beyond intelligence alone.

110-119: High Average

Scores in this range indicate above-average intelligence, placing individuals in roughly the top 25% of the population. This range encompasses many successful professionals and students who perform well in academic and professional settings.

90-109: Average

The majority of people fall within this range, representing normal cognitive functioning. This range includes approximately 50% of the population and encompasses a wide variety of abilities and achievements. Most people in this range can successfully complete standard educational programs and perform well in most occupations.

80-89: Low Average

This range represents below-average but still within normal limits. Individuals may require additional support in some academic or professional contexts but can typically function independently in daily life.

70-79: Borderline

Scores in this range may indicate learning difficulties or the need for additional educational support. Professional assessment is recommended to determine appropriate interventions.

Below 70: May Indicate Intellectual Disability

Scores below 70 may indicate intellectual disability, but this requires comprehensive professional assessment including adaptive functioning evaluation. Online tests cannot diagnose intellectual disability.

Percentiles: Understanding Your Position

IQ scores are often accompanied by percentile rankings, which indicate what percentage of the population scores below your score. For example:

An IQ of 100 corresponds to the 50th percentile (average)
An IQ of 115 corresponds to approximately the 84th percentile
An IQ of 130 corresponds to approximately the 98th percentile

Percentiles provide a more intuitive way to understand your score relative to others. A 90th percentile score means you scored higher than 90% of the population.

Factors That Influence IQ Scores

IQ scores are influenced by multiple factors, including:

Genetics: Research suggests that genetic factors account for approximately 50-80% of IQ variation (Plomin et al., 2016)
Environment: Educational opportunities, nutrition, and socioeconomic factors play significant roles
Age: IQ scores are age-adjusted, meaning your score is compared to others in your age group
Test Conditions: Fatigue, stress, and testing environment can affect performance
Cultural Factors: Some tests may have cultural biases that affect scores

Limitations of IQ Scores

It's crucial to understand what IQ scores don't measure:

Creativity: IQ tests measure convergent thinking, not creative or divergent thinking
Emotional Intelligence: The ability to understand and manage emotions is separate from IQ
Practical Skills: Street smarts, common sense, and practical problem-solving aren't fully captured
Motivation: A high IQ doesn't guarantee motivation or achievement
Multiple Intelligences: Howard Gardner's theory suggests intelligence has multiple forms beyond what IQ tests measure

How Our IQ Tests Calculate Scores

Our IQ tests use a norm-referenced scoring system based on the performance of other test-takers. This approach, inspired by established psychometric principles, ensures that scores are meaningful and comparable. The calculation considers:

Accuracy: The percentage of questions answered correctly
Time Efficiency: How quickly you solve problems compared to others with similar accuracy
Sample Size: As more people take our tests, the sample size grows, making percentile rankings more accurate

This methodology follows principles similar to those used in professional assessments, where scores are calibrated against representative samples. The larger our database of test-takers becomes, the more accurately we can represent the general population distribution.

Interpreting Your Results

When interpreting your IQ score, remember:

IQ is just one measure of cognitive ability, not a complete picture of intelligence
Scores can vary slightly between different tests and testing sessions
Online tests provide estimates, not clinical diagnoses
Focus on understanding your cognitive strengths and areas for growth
Consider your score in context of your life experiences and achievements

Conclusion

IQ scores provide valuable insights into cognitive abilities, but they're most useful when understood in context. They represent one aspect of human intelligence and should be considered alongside other factors like creativity, emotional intelligence, and practical skills. Whether your score is high, average, or below average, remember that intelligence is multifaceted, and your IQ score is just one piece of a much larger puzzle.

For more information about IQ testing, see our articles on Types of IQ Tests and How IQ Tests Are Scored.

References

Plomin, R., DeFries, J. C., Knopik, V. S., & Neiderhiser, J. M. (2016). Top 10 Replicated Findings From Behavioral Genetics. Perspectives on Psychological Science, 11(1), 3-23.
Wechsler, D. (2008). Wechsler Adult Intelligence Scale–Fourth Edition (WAIS–IV). San Antonio, TX: NCS Pearson.
Gardner, H. (1983). Frames of Mind: The Theory of Multiple Intelligences. New York: Basic Books.