The 20 Best Online IQ Tests

An IQ or "intelligence quotient" test aims to assess a person's intellectual abilities in areas like reasoning, problem solving, spatial imagery, and memory. The general concept of IQ emerged in the early 1900s as psychologists searched for a way to identify students who may need additional support. Since then, IQ testing has remained controversial but continues to be one of the most widely recognized ways to measure intelligence.

While online IQ tests cannot replace professionally administered ones, they can be a fun way to challenge your brain and get a general idea of your cognitive abilities. Whether you're curious about your cognitive abilities, looking for a mental challenge, or simply want to have some fun, this page offers a comprehensive guide to a wide range of options.

Here are 20 of the best and most popular online IQ tests, with brief reviews and links:

The average IQ score on most standardized tests is 100. Two-thirds of people score between 85 and 115. An IQ over 140 is considered genius level. Less than 0.1% score over 145. An exceptionally low IQ under 70 may indicate an intellectual disability. However, many experts argue that IQ tests alone should not determine a person's overall intelligence or success. Factors like education quality, test skills, illness, and emotional intelligence also play an important role.

There are many different types of IQ tests designed to assess both children and adults. Some of the most scientifically valid and reliable IQ tests are the Stanford-Binet Test, Woodcock-Johnson Tests of Cognitive Abilities, Wechsler Adult Intelligence Scale (WAIS), and the Wechsler Intelligence Scale for Children (WISC). These tests are revised and normalized regularly to ensure they reflect current social trends and remain free of cultural bias. Other online or abbreviated IQ tests may lack completeness and scientific rigor. Taking an official IQ test administered by a qualified professional can provide the most accurate results.

On most modern IQ tests, raw scores accounting for age are converted to a scale where 100 represents the average. Standard deviations in IQ scores follow a normal bell curve distribution in the population. Each standard deviation represents 15 IQ points above or below the mean. For example, about 2% score under 70 (2 SD below average) while about 2% score over 130 (2 SD above average). This allows IQ scores to represent a range of intellectual ability relative to peers of the same age group. As revised tests increase in difficulty, the raw scores equating to 100 may be adjusted so the normalized distribution stays centered on 100 representing average intelligence.

Contrary to what some websites may claim, there is little evidence that "exercising" your brain with games and puzzles before taking an IQ test will raise your score. However, reviewing practice questions can familiarize you with some of the types of questions asked and reduce test anxiety. If retaking the same IQ test, practice effects may artificially inflate scores by 10-20 points. For the most accurate results, it is best to wait at least six months between testing sessions using alternate or updated test versions.

Some individuals, such as chess master Judit Polgar (IQ 170) and physicist Christopher Hirata (IQ 225) distinguished themselves with extremely high scores from a young age. Writer Marilyn vos Savant gained fame in the 1980s for her listed IQ score of 228 in the Guinness Book of Records. However, as IQ tests become more difficult at higher ends of the scale, these exceptionally high scores are subject to greater statistical error. Most modern psychologists believe that while tests can identify disability well at lower ends, they lack precision at the genius level. For scores over 160, additional qualitative achievements should also be assessed when considering a true "genius-level" IQ.

Research indicates that IQ is fairly stable over time but can change gradually throughout the lifespan. Education, new experiences, aging, illness, trauma, stress, cultural differences, and test-taking skills may account for IQ score fluctuations of around 10-20 points in either direction over decades. However, someone's general range of cognitive abilities tends to stay relatively consistent from childhood through adulthood, especially when using the same standardized tests and adjusting for practice effects.

Critics argue that traditional IQ tests may contain cultural, racial, or socioeconomic biases that can lower scores for certain groups and overestimate abilities in more privileged groups. However, test creators work to eliminate bias by continually re-norming tests on representative populations and removing or replacing potentially problematic test items. Modern professionally-developed IQ tests used in clinical settings aim to eliminate factors like language level, cultural knowledge, and school quality that could unfairly impact scores. Still, factors including test anxiety, self-confidence, and attitude can subtly influence results.

The term "IQ" stands for "Intelligence Quotient," coined by German psychologist William Stern in 1912.

The average IQ score is around 100, with a standard deviation of 15. This means most scores fall within the range of 85-115.

IQ tests aren't solely about math and logic! They often assess spatial reasoning, vocabulary, memory, and processing speed.

Contrary to popular belief, IQ scores aren't static. They can fluctuate slightly over time due to various factors like education, environment, and even practice.

Despite their popularity, IQ tests are not without critics who argue they can be culturally biased and fail to capture the full spectrum of human intelligence.

The highest recorded IQ score ever claimed is 230, though its verification remains controversial.

The first IQ test was developed in France in 1905 by Alfred Binet and Theodore Simon to identify children struggling in school.

Some animals, like chimpanzees, crows, and even dolphins, have shown impressive scores on certain IQ-style tests.

Playing brain training games may not significantly boost your IQ but could sharpen some cognitive skills like memory and attention.

Studies suggest that bilingualism might be linked to higher IQ scores, possibly due to increased cognitive flexibility.

Albert Einstein's IQ is often estimated to be around 160, but there's no evidence he ever took a formal IQ test.

Stephen Hawking famously scored poorly on a childhood IQ test, indicating that traditional tests may not capture all forms of intelligence.

Leonardo da Vinci's exceptional creativity and diverse talents suggest an unconventional form of intelligence that wouldn't necessarily be reflected in a standard IQ test.

The largest collection of IQ tests online belongs to the Open-Psychometrics Project, featuring over 800 free tests for various cognitive skills. They offer a diverse range of free tests, including full-scale IQ tests, cognitive domain-specific tests, and personality assessments. It's a valuable resource for anyone interested in exploring their cognitive abilities and learning more about various intelligence assessment methods.

Also check out our collection of the 10 best brain game apps.