What is IQ?

IQ (Intelligence Quotient) is a standardized way to estimate general cognitive ability compared to the wider population. Scores are normed so that the average is 100 and the standard deviation is 15, forming a bell-curve distribution.

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100  = Mean
15  = Standard Deviation
~50%  score 90–109

Definition

IQ is a norm-referenced score derived from performance on tasks that sample core mental abilities: reasoning, pattern recognition, verbal understanding, spatial processing, working memory, and processing speed.

Because scores are normed by age group, your result reflects how you performed relative to people your age.

How Scores Are Interpreted

The IQ scale is centered at 100. Moving one standard deviation (15 points) above or below indicates stronger or weaker performance relative to average. Percentiles show how many people you outperformed.

Example: 50% of people fall roughly between 90 and 109 (“Average”).

IQ Bands at a Glance

IQ Range
Classification
% of Population
Visual Distribution
130+
Very Superior — exceptional problem solving and learning speed
≈ 2.2%
120–129
Superior — well above average analytical performance
≈ 6.7%
110–119
High Average — above-average reasoning and comprehension
≈ 16.1%
90–109
Average — typical range for the general population
≈ 50%
80–89
Low Average — somewhat below typical adult performance
≈ 16.1%
70–79
Borderline — markedly below average
≈ 6.7%
< 70
Extremely Low — significant learning support may be needed
≈ 2.2%

For full details, see the IQ Test Scale.

What IQ Measures

  • Fluid reasoning (novel problem-solving)
  • Pattern recognition and abstraction
  • Verbal comprehension (vocabulary, analogies)
  • Spatial processing (mental rotation, visualization)
  • Working memory (holding/manipulating info)
  • Processing speed (accuracy under time)

What IQ Doesn’t Measure

  • Emotional intelligence (EQ), empathy, motivation
  • Creativity, imagination, practical wisdom
  • Character, grit, values, social skills
  • Domain knowledge and life experience

Common Types of IQ Tests

Wechsler Scales (WAIS/WISC)

Widely used clinical batteries for adults and children; multiple subtests across verbal, reasoning, memory, and speed.

Stanford–Binet

Historically influential; modern editions align with the mean-100 / SD-15 standard.

Raven’s Matrices

Culture-reduced, nonverbal reasoning via visual patterns and analogies.

Factors That Influence Scores

  • Test conditions: noise, interruptions, device size
  • Fatigue, stress, anxiety on test day
  • Language proficiency for verbal items
  • Practice effects from repeated exposure
  • Health & sleep in the prior 24–48 hours
  • Motivation & engagement during testing

Tip: Take the test in a quiet place, on a larger screen if possible, and allow 5–10 minutes of uninterrupted focus.

Reliability, Validity & Ethical Use

  • Reliability: well-constructed tests produce stable scores across occasions.
  • Validity: scores should reflect the targeted abilities (e.g., reasoning), not unrelated factors.
  • Norms: results are interpreted against age-based reference groups.
  • Ethics: avoid using IQ as a sole label; consider context, strengths, goals, and opportunities.

FAQs

Is IQ fixed or can it change?

Core ability is relatively stable, but scores can vary with health, learning, familiarity, and conditions. Good sleep and focus often improve performance.

What’s a percentile?

A percentile shows how you rank relative to others. For example, the 84th percentile means you scored better than 84% of your age group.

Can I improve my IQ score?

You can optimize performance (rest, practice reasoning tasks, reduce anxiety). Broader skills—knowledge, strategy, EQ—grow with learning and experience.

Does a high IQ guarantee success?

No. Success also depends on motivation, habits, social skills, resilience, and opportunities.

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