What Is IQ?

IQ (Intelligence Quotient) is a numerical score that represents an individual's cognitive abilities. In modern IQ tests, the average score is set at 100 with a standard deviation of 15. This means roughly 68% of the population falls between an IQ of 85 and 115.

However, IQ does not capture the full spectrum of human intelligence. It measures specific cognitive abilities such as logical reasoning, spatial awareness, and verbal comprehension. Creativity, emotional intelligence, and practical intelligence are considered separate domains.

The History of IQ Testing

The Binet-Simon Scale (1905)

French psychologists Alfred Binet and Théodore Simon developed the first intelligence test to identify children who needed additional academic support. Their test introduced the concept of mental age, comparing a child's cognitive development to that of their peers.

The Stanford-Binet Test (1916)

Lewis Terman of Stanford University translated and standardized the Binet test for English speakers. This is when the IQ formula was first introduced:

IQ = (Mental Age / Chronological Age) × 100

For example, a 10-year-old performing at a 12-year-old level would have an IQ of 120.

The Wechsler Scales (1939)

David Wechsler developed the Wechsler Adult Intelligence Scale (WAIS), introducing the concept of the deviation IQ. Instead of using mental age ratios, this approach statistically compares an individual's performance to others in the same age group. Most modern IQ tests follow this method.

What IQ Tests Measure

Modern IQ tests typically assess the following areas:

1. Verbal comprehension: Vocabulary, reading comprehension, and verbal reasoning
2. Perceptual reasoning: Pattern recognition, spatial visualization, and non-verbal reasoning
3. Working memory: The ability to temporarily store and manipulate information
4. Processing speed: The ability to perform simple cognitive tasks quickly and accurately

IQ Score Distribution and Meaning

IQ Range	Classification	Population Share
130+	Very Superior	~2.2%
120–129	Superior	~6.7%
110–119	High Average	~16.1%
90–109	Average	~50%
80–89	Low Average	~16.1%
70–79	Borderline	~6.7%
Below 70	Requires Support	~2.2%

Common Misconceptions About IQ

"IQ is entirely innate"

While genetics play a significant role in IQ, environmental factors — education, nutrition, and cognitive stimulation — also matter greatly. Childhood environment, in particular, has a major impact on IQ development.

"A high IQ guarantees success"

IQ correlates with academic achievement, but its relationship with career success or life satisfaction is much weaker. Traits like conscientiousness, social skills, and emotional intelligence often play a larger role in real-world outcomes.

"IQ never changes"

IQ can shift over the course of a lifetime. Consistent learning, cognitive training, and healthy lifestyle habits can all improve cognitive ability.

Test Your Cognitive Abilities

The most accurate IQ assessments are administered individually by a licensed psychologist. However, you can get a quick sense of your logical reasoning and pattern recognition skills online. Give it a try with the service below.