What is a Good IQ Score? The Complete IQ Scale Explained

IQ scores are one of psychology's most powerful and most misunderstood metrics. Here is a complete, honest breakdown of what the numbers mean, how the scale works, and what IQ actually predicts (and does not predict) in real life.

The Complete IQ Scale

IQ Range	Classification	Population	Description
145+	Profoundly Gifted	0.1%	One in a thousand
130–144	Highly Gifted	2%	Mensa eligible (top 2%)
120–129	Superior	7%	Typical of PhDs
110–119	High Average	16%	Typical college graduate
90–109	Average	50%	Population center
80–89	Low Average	16%	Below average range
70–79	Borderline	7%	Clinical significance threshold
<70	Intellectual Disability	2%	Clinical diagnostic range

What IQ Tests Actually Measure

Modern IQ tests (WAIS-IV, WISC-V) do not measure a single "intelligence" — they sample four primary cognitive domains and combine them into a Full Scale IQ (FSIQ):

• Verbal Comprehension Index (VCI): Vocabulary, general knowledge, verbal reasoning — crystallized intelligence
• Perceptual Reasoning Index (PRI): Pattern recognition, spatial reasoning, matrix problems — fluid intelligence
• Working Memory Index (WMI): Digit span, arithmetic — working memory capacity
• Processing Speed Index (PSI): Coding, symbol search — neural speed

Each index score has independent predictive value for different real-world outcomes. A single IQ number hides important profile variation.

What IQ Predicts

IQ is one of the most predictive measures in all of behavioral science. Meta-analytic correlations:

• Academic performance: r≈0.5 — strong predictor across all educational levels
• Job performance: r≈0.4–0.5 — especially for complex jobs
• Income: r≈0.3 — meaningful but with large variance
• Health outcomes: r≈0.3 — higher IQ associated with better health literacy
• Longevity: r≈0.25 — higher IQ correlates with longer lifespan

What IQ Does Not Predict Well

IQ is a poor predictor of wisdom, ethical behavior, creativity, leadership effectiveness, relationship success, and happiness. Many high-impact professionals — across business, politics, and the arts — succeed through a combination of moderate cognitive ability, high conscientiousness, emotional intelligence, and domain-specific expertise that IQ tests do not capture.

Can IQ Change?

IQ scores are relatively stable in adulthood — correlations between childhood and adult IQ are around r=0.5–0.7. However, significant life events, education, and health can produce meaningful shifts. Childhood IQ scores are less stable than adult scores. The Flynn Effect — the documented 3-point-per-decade rise in raw IQ scores across populations throughout the 20th century — demonstrates that environmental factors substantially influence measured intelligence at the population level.

Take our Mini IQ Test for a free estimate across four cognitive domains, or Pattern Recognition for a pure fluid intelligence measure.