Learn about IQ & intelligence
Plain-English guides to IQ scores, scales, percentiles and what the research actually says — so you know exactly what your results mean.
Start with the IQ scale and score chart if you want the core framework — every range, level and classification rating — then use the IQ percentile calculator for exact score-by-score lookups. If you are deciding which test to take at all, we also compare the best online IQ tests on price, length and renewal terms — ourselves included — and put the two subscription products head to head in IQ Revealed vs myiq.com.
Free toolIQ Percentile Calculator →Enter any IQ score and instantly see its percentile, rarity and classification.What Is the Average IQ? Average Intelligence, the Normal IQ Range and the US Average
The average IQ score is 100 by definition. What counts as a normal IQ, the average IQ in the USA, why there is no measured world average IQ, and why country rankings disagree.
Read the guide →IQ Test for Kids: How Children Are Really Tested
How a real IQ test for kids works: the WISC-V, WPPSI-IV and Stanford-Binet, what age to test, what a child's score means, and why free online kids' IQ tests are not measurement.
Read the guide →What Is a High IQ? Where High and Good IQ Scores Begin
A high IQ is usually 130 or above — the top 2%. See what is considered a high IQ score, where a good IQ starts, and what 110, 120, 125 and 130 actually mean.
Read the guide →The IQ Scale and IQ Score Chart: All IQ Ranges, Levels and Ratings
The complete IQ score chart: every IQ range and level with its rating and percentile, plus the bell curve behind the scale and why published charts disagree.
Read the guide →IQ Test Questions: Sample Questions With Answers and Explanations
Sample IQ test questions with answers and worked explanations: matrix reasoning, number sequences, verbal analogies and spatial rotation, plus how to practice.
Read the guide →Average IQ by Age: How Scores Are Adjusted Across a Lifetime
IQ is age-normed, so the average is 100 at every age — but raw abilities rise and fall. How fluid and crystallized intelligence change by decade.
Read the guide →The Highest IQ Ever Recorded: Who Has the Highest IQ in the World?
Marilyn vos Savant’s 228 is the highest IQ ever recorded, but no modern test can produce it. What the highest possible IQ is, and which claims are verified.
Read the guide →Can You Increase Your IQ? How to Raise a Score, and by How Much
Can IQ be improved? Education adds roughly 1–5 points per extra year of schooling, while brain training mostly fails to transfer. What the evidence says.
Read the guide →How IQ Tests Work: What an IQ Test Measures and How IQ Is Calculated
What does an IQ test measure, and how is IQ calculated? The abilities each test samples, how a raw score is measured against a norming sample, and how deviation scoring turns it into a number.
Read the guide →Are IQ Tests Accurate? How Reliable IQ Scores Really Are
How accurate are IQ tests? A well-built test carries a margin of error of roughly ±5 to ±7 points. See what reliability, validity and IQ test accuracy actually mean.
Read the guide →Cognitive Ability Tests: Types, Uses and How to Prepare
Cognitive ability tests measure reasoning, memory and processing speed — used in hiring, education and self-assessment. Here's what they cover and how to prepare.
Read the guide →The 9 Enneagram Types Explained: Which One Are You?
A clear guide to the nine Enneagram personality types — core motivations, fears, strengths and growth paths — plus how the Enneagram compares to trait-based tests.
Read the guide →Type A vs Type B Personality: Traits, Myths and the Research
Driven and deadline-focused, or relaxed and flexible? What Type A and Type B actually mean, where the theory came from, and what modern research says.
Read the guide →How to Make a Career Change: A Practical, Evidence-Based Guide
Thinking about changing careers? A step-by-step framework: assess your interests and strengths, test-drive options, manage the finances and make the switch.
Read the guide →The Mensa IQ Test: Requirements, Minimum IQ and How to Join
Mensa requires a supervised score at the 98th percentile — a minimum IQ of about 130–132 on an SD-15 scale, 148 on Cattell. The admission test and how to join.
Read the guide →EQ vs IQ: The Difference Between IQ and EQ, and Which Matters More
IQ measures reasoning ability; EQ describes how well you read and manage emotions. How each is measured, and why the two overlap less than people assume.
Read the guide →Fluid and Crystallized Intelligence: Definitions, Examples and Differences
Fluid intelligence solves novel problems; crystallized intelligence applies knowledge. Clear definitions, examples of each, and how both change with age.
Read the guide →Career Aptitude Tests: What They Measure and How to Use One
Career aptitude tests combine interests, strengths and working style to suggest fitting fields. What good tests measure, what to ignore, and how to act on results.
Read the guide →Personality Type Compatibility: How the 16 Types Get Along
Compatibility chart for all 16 personality types: the easiest, complementary and hardest match for every four-letter code — and what it can't predict.
Read the guide →The Smartest Personality Type: What the Evidence Actually Shows
Which personality type has the highest IQ? No credible data ranks the 16 types by intelligence. Here's where the rankings come from, what research does show, and how to measure ability properly.
Read the guide →Is myiq.com Legit? An Honest Look at How It Works
Is myiq.com a scam or legit? How the myiq.com IQ test and subscription actually work, what its Trustpilot reviews show, how to cancel, and what to check before paying.
Read the guide →How to Cancel a myiq.com Subscription (Step by Step)
Every way to cancel myiq.com — portal, profile, support email — what the myiq.com/us billing page is for, and how to read the charges on your statement.
Read the guide →Savant Syndrome: The Islands of Ability, and What IQ Really Shows
What savant syndrome is, why about half of savants are autistic, what IQ actually shows in savant syndrome and autism, and how acquired savants differ.
Read the guide →Twice-Exceptional (2e): Gifted With ADHD, Autism or a Learning Disability
What twice-exceptional (2e) means, why gifted students with ADHD or autism are missed, and what an IQ profile really shows when the two sit in one person.
Read the guide →Is 16 Personalities Accurate? What Psychometrics Says
How accurate is the 16 personalities test? What type frameworks can and can't measure, what test-retest research shows, and how to get value from a type result anyway.
Read the guide →Types of Intelligence: Gardner's Multiple Intelligences and What the Evidence Says
How many types of intelligence are there? Gardner's eight (or nine) multiple intelligences, why the count keeps changing, and what the research actually supports.
Read the guide →Is Intelligence Genetic? What Heritability Really Means
Is intelligence genetic? Heritability runs from about 20% in infancy to 80% in adulthood — what that statistic means, what it does not mean, and what raises scores.
Read the guide →Learning Styles: The Four Types, and What the Evidence Says About Matching Teaching to Them
Visual, auditory, reading/writing, kinesthetic: what the four learning styles are, why matching teaching to them keeps failing in trials, and what raises learning instead.
Read the guide →Left Brain vs Right Brain: What the Research Actually Shows
Are there left-brained and right-brained people? An imaging study of 1,011 brains says no — what the hemispheres really do, and where the idea came from.
Read the guide →Photographic Memory: Does It Exist, and Does It Mean a High IQ?
No adult has ever demonstrated a photographic memory under test. What eidetic imagery actually is, why it fades by adulthood, and what real exceptional memory looks like.
Read the guide →The Dunning-Kruger Effect: What the Research Actually Found
The Dunning-Kruger effect is smaller than its reputation. What the 1999 study found, why the famous curve is not in it, and what happened when it was tested on IQ.
Read the guide →Neuroplasticity: How the Brain Changes, and What It Cannot Do
Neuroplasticity is the brain's ability to change with experience. How it works, what taxi drivers showed, the new-neuron dispute, and why brain training rarely transfers.
Read the guide →Growth Mindset vs Fixed Mindset: What the Research Actually Shows
A growth mindset is the belief that ability can be developed. What Dweck found, how common it is, what the meta-analyses show, and whether it makes you smarter.
Read the guide →Cognitive Bias: Types, Examples, and Whether Intelligence Protects You
A cognitive bias is a systematic error in judgement. The main types with examples, how much of the research replicated, and whether a high IQ protects you.
Read the guide →Memory Palace: How the Method of Loci Works, and Whether It Works
How to build a memory palace, what the method of loci is, and what the research shows — including why memory champions are not more intelligent, just trained.
Read the guide →Attention Span: What Is Actually Measured, and the Eight-Second Myth
The eight-second attention span has no research behind it. What is actually measured — screen switching, vigilance, attention in lectures — and what it means for a test score.
Read the guide →Stereotype Threat: What It Is, and What the Evidence Actually Shows
What stereotype threat is, the claim the original 1995 study never made, and where the research has failed to replicate — and what all of that means for a test score.
Read the guide →Critical Thinking: What It Is, the Core Skills, and How It Differs From IQ
Critical thinking is purposeful, self-regulating judgement. The six core skills, examples, whether critical thinkers are smarter, and what teaching it achieves.
Read the guide →Executive Function: The Three Core Skills, and How They Differ From IQ
Executive function is the brain's control system: working memory, inhibition and cognitive flexibility. What the research shows, and why only one of the three tracks IQ.
Read the guide →Lateral Thinking: What It Is, and What the Evidence Actually Shows
Lateral thinking means attacking a problem from an unexpected angle. Where the term came from, how it differs from divergent thinking, and what testing showed.
Read the guide →Deductive vs Inductive Reasoning: The Difference, and Which One IQ Tests Measure
Deduction applies a rule and is certain; induction generalises from cases and is probable. What each one guarantees, and which of the two IQ tests actually measure.
Read the guide →Aphantasia: What It Is, and Is It Linked to IQ?
Aphantasia is the inability to picture things in the mind's eye. How common it is, how researchers confirm it, and what studies show about aphantasia and IQ.
Read the guide →Metacognition: What It Is, Examples, and Is It Linked to IQ?
Metacognition is thinking about your own thinking. What it means, everyday examples, the study strategies that work, and what research shows about metacognition and IQ.
Read the guide →Is IQ Center Legit? What Its Own Terms Say About the Test and the Bill
Is iqcenter.com legit? Its own terms call it an entertainment product, not an IQ test. What the iq-test-help.com charge is, how the trial renews, how to cancel and what reviews show.
Read the guide →The Flynn Effect: Why IQ Scores Rose — and Why They Are Now Falling
The Flynn effect is the rise in IQ scores of about 3 points per decade. What it is, how big the gains were, what causes it, the reverse Flynn effect and what it means for your score.
Read the guide →Working Memory: What It Is, How Much It Holds and How It Relates to IQ
Working memory is the mental workspace that holds a few items while you use them. The Baddeley model, why the limit is about four chunks not seven, its link to IQ, testing, training and ADHD.
Read the guide →Spatial Reasoning: What It Is, How It Is Tested and How It Relates to IQ
Spatial reasoning is the ability to picture objects and work out how they look when turned, folded or moved. Mental rotation, how it is tested, its link to IQ and STEM, sex differences and training.
Read the guide →Cognitive Load: What It Is, the Three Types and How to Reduce It
Cognitive load is how much working memory a task uses. Sweller's theory, the three types (intrinsic, extraneous, germane), worked examples, split attention, cognitive overload and how it relates to IQ.
Read the guide →The g Factor: What General Intelligence Is and How It Relates to IQ
The g factor is what scores on very different mental tests have in common. Spearman's two-factor theory, g loadings, g vs IQ, what g predicts, whether education raises it, and the leading criticisms.
Read the guide →Dual N-Back: What It Is, How to Do It and Whether It Raises IQ
Dual n-back is a memory task that tracks two streams at once. How it works, how to do it, the 2008 study behind the brain-training craze, and what later trials found about IQ and ADHD.
Read the guide →Piaget's Stages of Cognitive Development: The 4 Stages Explained
Piaget's theory of cognitive development in four stages — sensorimotor, preoperational, concrete and formal operational — with ages, examples, how it began with an intelligence test, and what later research changed.
Read the guide →Cognitive Flexibility: What It Is, How It's Measured and Its Link to IQ
Cognitive flexibility is the ability to switch between rules, tasks and points of view. What it is, everyday examples, how psychologists measure it, how it relates to IQ, and what the evidence says about improving it.
Read the guide →Raven's Progressive Matrices: What the Test Measures, Its Versions and How It Is Scored
Raven's Progressive Matrices is a non-verbal reasoning test first published in 1938. What it measures, the SPM, CPM, APM and Raven's 2 versions, how scores and norms work, and whether online Raven tests are real.
Read the guide →Stanford-Binet Test: What the SB5 Measures, How It Is Scored and Its History
The Stanford-Binet is an individually administered IQ test for ages 2 to 85+. What the SB5 measures, its five factors and ten subtests, how scores work, its history since 1905, and whether online versions are real.
Read the guide →Wisconsin Card Sorting Test (WCST): How It Works, Scoring and What It Measures
The Wisconsin Card Sorting Test measures flexible thinking: sort cards by a hidden rule that changes without warning. How it works, perseverative errors and other scores, versions, and how it relates to IQ.
Read the guide →The Mozart Effect: Does Classical Music Make You Smarter?
The Mozart effect says listening to Mozart makes you smarter. What the 1993 study really found, why it failed to replicate, why music can briefly lift scores, and whether Mozart for babies or music lessons raise IQ.
Read the guide →Do We Only Use 10% of Our Brain? The Myth, Explained
No, we don't only use 10% of our brain. How much we really use, the grain of truth behind the myth, where the 10% figure came from, who still believes it, and whether using more would raise your IQ.
Read the guide →Does Reading Make You Smarter? What the Research Shows
Yes — mainly through vocabulary, knowledge and verbal reasoning. What the twin studies and meta-analyses show, whether reading raises IQ, fiction vs nonfiction, books vs social media, and how much to read.
Read the guide →Does Chess Make You Smarter? What the Research Shows
No good evidence that chess raises IQ. Why chess players score a little higher, what the school trials found, what chess does improve, and whether it is good for the brain.
Read the guide →Signs of High Intelligence: What the Research Actually Supports
The signs of a high IQ that research supports — fast learning, reasoning, vocabulary, working memory, curiosity — the viral habits that do not hold up, and how well people judge intelligence in others and themselves.
Read the guide →Triarchic Theory of Intelligence: Sternberg's Three Abilities and the Evidence
Sternberg's triarchic theory of intelligence: analytical, creative and practical intelligence with examples, how the theory was tested, the main criticisms, and how it differs from Gardner and g.
Read the guide →IQ Revealed is not affiliated with, endorsed by or connected to Pearson, Riverside Insights, Mensa, 16Personalities, NERIS Analytics, The Myers-Briggs Company, the Enneagram Institute or any publisher of the tests and frameworks named in the guides above, and does not administer or score them. They are named only so that the material these guides describe can be traced back to where it actually comes from.