The Stanford-Binet test is one of the oldest and most widely used intelligence tests in the world, first published in 1916 and now in its fifth edition (SB5). It measures cognitive abilities across multiple domains and produces an IQ score with a mean of 100 and a standard deviation of 15. The test is administered individually by a trained professional and can be given to anyone from age 2 through 85 and older.
What the Test Measures
The SB5 evaluates five cognitive factors: fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing, and working memory. Each factor is tested through both verbal and nonverbal subtests, producing ten subtest scores in total. This split between verbal and nonverbal domains is one of the test’s defining features. The nonverbal subtests are particularly useful for people with limited English proficiency, hearing impairments, learning disabilities, traumatic brain injury, or autism spectrum disorders, since they don’t rely heavily on spoken language.
Together, these subtests generate a Full Scale IQ (FSIQ) score. The test also produces separate Nonverbal IQ and Verbal IQ composite scores, along with individual factor index scores. This breakdown lets evaluators see not just overall intelligence but specific cognitive strengths and weaknesses.
How Scoring Works
Like most modern intelligence tests, the SB5 uses a scoring scale centered at 100, where roughly 68% of the population scores between 85 and 115. A score of 130 or above is generally considered the gifted range, while scores below 70 may indicate an intellectual disability.
One feature that sets the Stanford-Binet apart from other IQ tests is its Extended IQ scale, which can calculate scores higher than 160 and lower than 40. Most other intelligence tests hit a ceiling well before that. This makes the SB5 especially valuable at both ends of the spectrum, whether identifying children who are profoundly gifted or diagnosing significant cognitive impairments. The extended range is possible because the test includes a large number of both very difficult and very easy items.
Who Takes It and Why
The Stanford-Binet is used in schools, clinics, hospitals, and private practices for several purposes. The most common include gifted program placement, learning disability evaluations, developmental delay assessments, and neuropsychological evaluations following brain injuries. Courts and social services agencies also sometimes use it when cognitive ability is relevant to a legal or placement decision.
For gifted education, the Stanford-Binet has a long pedigree. Lewis Terman, who created the original American version, specifically designed his research to identify extremely gifted children. Today the test remains the intelligence measure of choice for identifying children at the highest ability levels: highly gifted (145 to 159 IQ), exceptionally gifted (160 to 179), and profoundly gifted (180 and above). Many gifted programs require an IQ score from an individually administered test like the SB5 for admission.
An Early SB5 version also exists for very young children. It focuses on detecting intellectual deficiencies, developmental delays, and disabilities early enough to allow intervention and referral for more detailed evaluations.
What the Testing Experience Looks Like
The SB5 is not a group test or something you take on a computer at home. A trained examiner, typically a psychologist or school psychologist, sits with you (or your child) one on one and administers the test using physical test booklets and manipulatives. The full battery generally takes between 45 minutes and 90 minutes, depending on the person’s age and ability level. Younger children and those being tested only on select subtests may finish more quickly.
The test begins with two routing subtests, one verbal and one nonverbal, that establish a starting difficulty level for the remaining subtests. This adaptive starting point means a 4-year-old isn’t wading through items meant for teenagers, and a gifted adolescent isn’t spending unnecessary time on easy questions. From there, the examiner works through the remaining subtests in order.
After the session, the examiner scores the responses and typically provides a written report that includes the FSIQ, composite scores, factor index scores, and a narrative interpretation of what the scores mean in practical terms.
How It Compares to Other IQ Tests
The Stanford-Binet’s main competitor is the Wechsler family of intelligence tests (WISC for children, WAIS for adults), which are also individually administered and produce a similar IQ scale. Both are considered gold-standard measures and are accepted by schools, clinicians, and courts. The biggest practical difference is at the extremes: the SB5’s extended scoring range makes it a better fit when the goal is to measure very high or very low cognitive ability with precision. If a child scores at the ceiling of a Wechsler test, an evaluator will often follow up with the Stanford-Binet to get a more accurate picture.
The SB5 also covers a wider age range in a single instrument, from age 2 through 85 and beyond, while the Wechsler tests use separate versions for different age groups. For longitudinal tracking of someone’s cognitive development over many years, the Stanford-Binet offers a consistent measuring tool across the lifespan.
Cost and Access
Because the SB5 requires a trained professional to administer and interpret, you can’t purchase or take it on your own. Testing is typically arranged through a school district (often at no cost if requested as part of a special education evaluation), a private psychologist, or a clinic. Private testing costs vary widely but often run several hundred dollars for the testing session and written report. If your child’s school is considering gifted placement or a learning disability diagnosis, the school psychologist may administer the SB5 or a comparable test as part of that process at no charge to you.