Discover what intelligence is, how it works, what intelligence tests measure and how they are scored. This background knowledge will help you to make more sense of your IQ (Intelligence Quotient) scores.
This section includes a list with links to some of the better free online IQ tests.
Please note, if you are a job seeker or candidate psychometric or aptitude tests rather than IQ tests, are used by many employers and recruiters. These tests focus on specific abilities required for a certain career or job rather than overall general intelligence (which is what this section is about). If this is what you are looking for then then check out our Free Online Psychometric Tests
Are you an active job seeker or candidate who is unfamiliar with the psychometric testing process? Do you need to improve your test taking speed, skills and confidence?
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Human intelligence is one of the most fiercely debated subjects within the field of psychology. There are researchers who suggest that intelligence is a single, general ability while others believe that intelligence encompasses a broader range of aptitudes, skills and talents. To avoid confusion (and that debate) this section focuses on a "general intelligence factor" that's measured and expressed as IQ.
There are almost as many definitions of IQ as there are psychologists however in 1994 a group of 52 experts in the study of intelligence and related fields endorsed the following definition of intelligence:
Intelligence is a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather it reflects a broader and deeper capability for comprehending our surroundings—“catching on,” “making sense” of things, or “figuring out” what to do. (Gottfredson, 1997)
IQ stands for "Intelligence Quotient". It is the single number derived from a set of standardised tests that measure a person’s ability to comprehend and solve problems in relation to their age group within the general population. These tests of mental ability reflect a single factor, usually abbreviated as "g" (by psychologists). This "g factor" corresponds closely to what the rest of us call intelligence.
The first IQ test was developed by two French scientist, Alfred Binet and Theodore Simon, originally for the purposes of assessing children at school so that mentally-handicapped children or children with behavioural problems could receive adequate and appropriate education. This initial test measured skills such as comprehension, judgement, problem-solving and reasoning – and is the basis of the standard modern intelligence test. The original test was modified for adults at Stanford University in the United States, with the new version being named the Stanford-Binet test and the score it produces is called the now famous “intelligence quotient” or IQ.
Individuals differ in their ’g factor’ and IQ tests measure those differences in ability by examining two areas of intelligence:
IQ tests measure fluid and crystallised intelligence by through a range of questions that assess different categories of intellectual ability. For example:
Scores for the different categories are combined and put through a process called factor analysis. This produces a final score that represents your IQ. It's the reduction of these different dimensions into a single general intelligence score that provokes debate within the field of psychology.
Intelligence test scores typically follow a normal distribution on a bell-shaped curve in which the majority of scores lie near or around the average score. On most IQ tests, a score between 90 and 110, (or the median 100 plus or minus 10) indicates average intelligence. As you look further toward the extreme ends of the curve scores tend to become less common.
(This is the Weschler Adult Intelligence Scale which is slightly different to the one below)
This infographic is an example of an incomplete scale based on some broad generalisations. The fact is if you score 95 you're also within the average IQ range - on most of the standard scales.The point is claiming an IQ of 97 or even 147 is meaningless unless you know the actual type of test that was used.
Over 140: Genius or near genius
120 - 140: Very superior intelligence
110 - 119: Superior intelligence
90 - 109: Normal or average intelligence
80 - 89: Dullness Normal
70 - 79: Mild
50 - 69: Moderate
20 - 49: Severe
Below 20: Profound
General intelligence is a key to determining many life outcomes such as academic success, job performance and advancement.
The importance of our general intelligence in job performance is related to complexity. Occupations differ considerably in the complexity of their demands, and as that complexity rises, higher levels of general intelligence become a bigger asset and lower levels a bigger handicap. The classification scales below reflect this and indicate how scores can be used to establish cut off points for entry into different types of jobs and educational programmes.
Best Estimate of IQ Differences for Adults in Different Occupations
(Wechsler Adult Intelligence Scale)
|WAIS-R Mean IQ Range||Occupational Category|
|110 -112||Professional and technical|
|103 -104||Managers, clerical, sales|
|100 -102||Skilled workers|
|92-94||Semi Skilled workers|
Kaufman, Alan S. Assessing Adolescent and Adult Intelligence. Allyn and Bacon, 1990
Measured Intelligence and Education
(Wechsler Adult Intelligence Scale)
|WAIS-R Mean IQ||Occupational Category|
|125||Mean of persons receiving Ph.D. and M.D. degrees|
|115||Mean of college/university graduates|
|105||Mean of high school graduates|
|100||Average for total population|
|75||About 50-50 chance of reaching ninth grade|
Matarazzo, Joseph D. Wechsler's Measure and Appraisal of Adult Intelligence, 5th Edition. Oxford University Press, 1972.
The value of IQ tests is that they measure general cognitive ability which has been proven to be a fairly accurate indicator of someone's intellectual potential. Being brighter also helps as the daily activities of everyday life require reasoning and decision making — an exercise of general intelligence. However, a person’s intelligence level doesn't guarantee either success or failure in life as many other personal traits and circumstances come into play. Daniel Goleman, a noted psychologist at Harvard University, puts it this way:
"I would say that IQ is the strongest predictor of which field you can get into and hold a job in, whether you can be an accountant, lawyer or nurse, for example. But once you are in that field, emotional intelligence emerges as a much stronger predictor of who will be most successful, because it is how we handle ourselves in our relationships that determines how well we do once we are in a given job."
The bottom line is that your IQ score will give you a pretty accurate indication of your ability to think, reason and solve problems which will have a bearing on many aspects of your life. However, IQ is not the be all end all of a person's abilities. IQ scores don't measure a myriad of other abilities that can lead to many different successes in life.
The world is full of smart people who do amazing things but experts disagree on exactly what makes a person a genius. Some specify a particular IQ score, such as 140 or higher, while those who disagree with the 140-point cutoff argue that people often display intelligence that can't be measured on a standardised IQ test. Dr. Abbie Salny, who was the American Mensa's supervisory psychologist for 23 years, had this to say in an excerpt from the Mensa Bulletin:
It has been said that a 140 IQ is a "genius" score, however there is no definition, as such, in either of my psychological dictionaries about "genius." Neither is there an IQ score ranked as "genius." Furthermore, a true genius may not score particularly well on a standard group IQ test. We know a Nobel Prize winner who never scored at Mensa level on a school IQ test - he was too busy seeing all the alternate possibilities for each answer. At the present time, all IQ scores are read off of tables. Now there are almost no tests in use that will give extraordinary high IQ's except those with very large standard deviations. And really, those who are what we may call a genius don't need a score to prove it.
Another respected psychologist Arthur Jensen reinforces this position but from a slightly different perspective. He states that IQ differences in the upper part of the scale have far less personal implications and are generally of lesser importance for success than certain traits of personality and character.
The World Genius Directory: Although there's no "official" genius score there are organisations, like Mensa, for the few who possess "extreme talent". The Genius Directory includes an up to date Who's Who of some of the highest IQ test scorers in the world.
While men and women may think differently, there's no evidence that either gender is innately more intelligent than the other.
What researchers have discovered is that when it comes to intelligence, people have two types of brains: One type has a significant amount of gray tissue (information processing centres), and a second type has a significant amount of white tissue (tissue that networks the information processing centres). The study found that female brains have about 10 times more white matter than male brains, and male brains have about 6.5 times more gray matter. What does this mean? While men and women have different types of tissue in their brains, overall performance is equal - we just excel at different types of tasks.
"The error of youth is to believe that intelligence is a substitute for experience, while the error of age is to believe experience is a substitute for intelligence”
Until the age of about 25, most of us improve our problem-solving skills and memory. We peak at about age 28, and then comes the slide, with each passing decade performance on standardised reasoning tests declines (our fluid intelligence). However, the good news is that the long-term memory of older adults appears to store and use information better than short-term memory (our crystallised intelligence) so, while older people may lack the cognitive skills of their youth, they have something that can't be measured on any standardised test - wisdom.
Wisdom, expertise and practical knowledge based on years of experience are valuable assets. Younger people may perform with greater speed and more agility, but the older generation can see the big picture, relationships and trends based on experience.
When it comes to testing, keep in mind that there are outside factors that may have a negative impact on your score - taking test on a bad day, being excessively nervous or spending too much time on a few difficult items can artificially lower your score. Understanding how an IQ test works, practice, familiarising yourself with the type of problems and being well rested will help you to achieve a truer score.
IQ tests measure your ability to understand ideas and not the quantity of your knowledge so learning new information does not automatically increase your IQ. There is evidence that maintaining an intellectually stimulating environment (by learning new skills) and some forms of specialised brain training boosts some ability but these changes aren't permanent. Scientists are working on it but they have yet to discover reliable and ethical ways to manipulate a permanent rise in IQ - which is why the now famous Flynn Effect is also known as the IQ paradox.
University of California, Irvine. "Intelligence In Men And Women Is A Gray And White Matter." ScienceDaily. Jan. 22, 2005. (Nov 19, 2010) Spearman, C. (1904). "General intelligence," objectively determined and measured. American Journal of Psychology 15, 201-293 Gottfredson, L. S. 1986 The g Factor in employment. Special issue of the Journal of Vocational Behavior, 29, 293-450. Herrnstein, R. J. & Murray, C. 1994 The Bell Curve: Intelligence and Class Structure in American Life. New York: The Free Press Jensen, A. 1980 p 113. Bias in Mental Testing. New York: Free Press
The IQ paradox is simply to do with the large gains over time in intelligence test scores. In his study of IQ tests scores for different populations over the past sixty years, Professor James Flynn discovered that IQ scores increased from one generation to the next for all of the countries for which data existed. This interesting phenomena has been called "the Flynn Effect." In this short (3 min) video Professor Flynn describes the global increase in IQ scores as well as some of the possible reasons.
James R. Flynn is an emeritus professor of politics at the University of Otago in New Zealand and author of "What Is Intelligence?: Beyond the Flynn Effect" and "Are We Getting Smarter? Rising IQ and the Twenty-First Century."
Our ancestors were grounded in the concrete world. They used classifications based on functional relationships (this eats that) or similarities in appearance (this looks like that). However over time, and in response to an increasingly complex world, people have developed new "habits of mind". These are more conceptual and have boosted IQ scores in specific categories - for example "similarities" has seen enormous gains (24 points between 1947 and 2002 in the Weschsler Intelligence Scale for Children). It would appear that people are not growing ‘smarter’ but they are growing better at very specific cognitive skills.
And IQ scores continue to climb as Flynn recently reported, “To my amazement, in the 21st century the increases are continuing. The latest data show the gains in America humming right along at the old rate of three tenths of a point a year.”
The Flynn Effect suggests that intelligence is more malleable and subject to environmental effects than originally thought. That said, researchers have yet to answer many of the questions about why this effect occurs and until they do, the Flynn effect will remain a paradox.
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Professional IQ Tests International High IQ Society | Free Online IQ Test
A multiple choice timed test consisting of 50 questions assessing your verbal, math and spatial reasoning and problem solving skills. The High IQ Society website states that they're the first to provide a range of standardised free IQ tests on the internet. And with more than 20 million users since 2001 their question pool enables them to provide more than 2.4 billion tests.
IQ Test | IQ Test - the original online test
In addition to measuring your general IQ, this test assesses your performance in 13 different areas of intelligence, revealing your key cognitive strengths and weaknesses.
Fun Mensa Test | Free Online IQ Test
From Mensa International this quiz is provided for entertainment purposes only; it is not an IQ test. Answers to questions and discussion of the answers are provided at the time you submit your answers. Mensa accepts anyone with an IQ score in the top two per cent of the population, measured on a recognised IQ test (Note there are several websites claiming to offer online 'Mensa IQ tests' however British Mensa does not currently operate an online IQ test and is unable to accept online test results as evidence for membership to the society)
Spatial Intelligence Test | Free Online IQ Test
This questionnaire includes 208 questions and provides you with a detailed feedback report. It measures your spatial intelligence - your ability to look at and understand the spatial world. The higher your spatial IQ, the more easily you will be able to learn and to solve problems that involve looking at and understanding what you see.
FunEducation | Free Online IQ Test
This free online IQ test with only 43 Questions measures several key areas including word analysis and spatial reasoning. Your raw IQ score is scaled to provide your IQ relative to the normal distribution of intelligence scores.
Test The Nation | BBC Free IQ Quiz
This not a recognised IQ test however, achievement of a score of 120 or more in this IQ quiz would suggest you might like to have a go at a full Mensa IQ test. You can also compare your results with the rest of the UK.
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