TLDR: The Most Accurate IQ Test According to Science is the Stanford-Binet 5 test.

Intelligence Quotient (IQ) tests are our most scientifically relevant tool used to measure human cognitive abilities. Their accuracy and reliability are important for educational placements and predicting future performance. This blog post explores the most scientifically validated IQ tests administered in proctored environments, ensuring the highest standard of accuracy. These tests are ranked by G factor from top to bottom.

1. Stanford-Binet Intelligence Scales, Fifth Edition (SB5)

The Stanford-Binet Intelligence Scales, Fifth Edition (SB5), is considered The Most Accurate IQ Test According to Science. Initially developed by Alfred Binet and later revised by Lewis Terman at Stanford University, the SB5 test assesses five factors of cognitive ability: Fluid Reasoning, Knowledge, Quantitative Reasoning, Visual-Spatial Processing, and Working Memory.

2. Wechsler Adult Intelligence Scale (WAIS)

The Wechsler Adult Intelligence Scale (WAIS) is another highly respected IQ test, used primarily for adults. Created by psychologist David Wechsler, the WAIS measures different aspects of intelligence through various subtests that cover verbal comprehension, perceptual reasoning, working memory, and processing speed.

3. Comprehensive Adult Intelligence Test (CAIT)

The Comprehensive Adult Intelligence Test (CAIT) serves as a free alternative to the WAIS. Although not as widely recognized as the WAIS, the CAIT is recommended for those seeking an accurate assessment online. It mirrors many of the WAIS’s testing methodologies, providing a viable option for remote intelligence testing.

4. Reynolds Intellectual Assessment Scales (RAIT)

Valued for its efficiency and effectiveness, particularly in educational and clinical settings for both children and adults. While the RAIT is effective and offers a quick means of assessing intelligence, it is usually not the first choice when an in-depth and nuanced understanding of an individual’s cognitive profile is required, such as might be sought in neuropsychological evaluations or high-stakes educational placements. It’s very well-suited for situations where a swift assessment is needed without sacrificing accuracy, but it doesn’t provide as broad a measurement spectrum as the SB5 or WAIS.

5. Additional Proctored IQ Tests

Here is a list of additional proctored IQ tests known for their accuracy:

Understanding IQ Scores

IQ scores are designed to measure a range of cognitive abilities and potential. They are typically scaled with a median score of 100, and a standard deviation of 15 points. Scores can generally be classified into different categories, such as average, above average, gifted, and extremely gifted.

How Does the IQ Scale Work?

The IQ scale is a norm-based score that ranks an individual’s cognitive abilities against a statistical norm. An IQ of 100 is considered average, with approximately 68% of the population scoring between 85 and 115. Higher or lower scores indicate higher or lower cognitive ability, respectively.

Who Invented IQ Tests?

The first practical intelligence tests were developed by Alfred Binet in France in the early 20th century, with the intention of identifying students who needed additional academic support. The concept was later expanded by other psychologists, notably Lewis Terman and David Wechsler.

The Evolution of the SB5 Test

Since its inception, the Stanford-Binet test has evolved through several revisions to improve its reliability and validity. The fifth edition, in particular, expanded the age range of test-takers and refined the assessment scales to better measure diverse aspects of intelligence.

The Inception of the WAIS Test

The WAIS was developed by David Wechsler in 1955. It was unique in that it provided separate scores for verbal and performance IQ, recognizing the multi-dimensional nature of intelligence.

Why Online Tests Can Be Inaccurate

Online IQ tests often lack the rigorous standards of proctored tests. They may not accurately measure intelligence due to uncontrolled testing conditions, the variability of test administration, and the lack of standardization.

Understanding G-loading

G-loading refers to the degree to which a test measures general intelligence (g-factor). Tests with high g-loading are considered more comprehensive and are better predictors of cognitive abilities across various domains.

How Norming Works

Norming involves administering a test to a large, representative sample of the population to establish norms or average scores. These norms are then used to interpret individual scores, providing a context for understanding an individual’s performance relative to others.

You and Your IQ

Your IQ score is a snapshot of your current cognitive abilities. It can provide insights into your strengths and weaknesses but is not an exhaustive representation of your potential or worth.

IQ Score Interpretation Table

IQ RangeClassification
130+Very Superior
110-119High Average
80-89Low Average
Below 70Extremely Low


Understanding the accuracy and implications of IQ tests is essential for their effective use in educational and psychological contexts. Proctored IQ tests, like those mentioned above, provide reliable and valid measures of intelligence, contributing significantly to our understanding of cognitive abilities.