The Stanford-Binet test is an individually administered IQ test: a trained examiner, usually a psychologist, gives a person a series of verbal and nonverbal tasks one-to-one and converts the results into IQ scores compared with people of the same age. The current edition, the Stanford-Binet Intelligence Scales, Fifth Edition (SB5), was published in 2003 and covers ages 2 to 85 and older. It measures five abilities — fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing and working memory — and reports a Full Scale IQ with an average of 100. It descends from the first modern intelligence test, built in Paris in 1905, which makes it one of the oldest lines of IQ tests still in use.
From Binet’s scale to the SB5
In 1905 the French psychologists Alfred Binet and Théodore Simon published a scale of short, graded tasks to identify children who needed special help at school. At Stanford University, Lewis Terman revised and extended it for American children; his 1916 book The Measurement of Intelligence reports that the revision was standardized on approximately 1,000 children, of whom 905 were between 5 and 14 years old. Terman’s version became known as the Stanford-Binet.
| Year | Edition | What changed |
|---|---|---|
| 1905 | Binet–Simon scale (France) | The first practical test of general intellectual level |
| 1916 | Stanford revision (Terman) | American norms; popularized the intelligence quotient |
| 1937 | Second edition (Terman & Merrill) | Two parallel forms, L and M |
| 1960 | Third edition, Form L-M | Combined form; a deviation IQ with a standard deviation of 16 |
| 1986 | Fourth edition (Thorndike, Hagen & Sattler) | Organized into subtests and broad ability areas |
| 2003 | Fifth edition, SB5 (Roid) | Five factors, verbal and nonverbal; standard deviation 15; ages 2–85+ |
The early editions scored children with a ratio IQ: mental age divided by chronological age, multiplied by 100. A ten-year-old who performed like a typical twelve-year-old scored 120. That works poorly for adults and exaggerates extreme scores, which is why modern editions compare a person directly with the spread of scores in their own age group. Our IQ scale guide covers the switch, and it is one reason the famous very high childhood IQs in our highest IQ ever article cannot be compared with scores on today’s tests.
What the SB5 measures
The SB5 is built around five factors, and each one is measured twice — once with a verbal subtest and once with a nonverbal subtest, where the person can answer by pointing or with objects instead of words. Five factors times two domains gives the ten subtests.
| Factor | What it covers |
|---|---|
| Fluid reasoning | Solving new problems and finding rules in patterns — see fluid vs crystallized intelligence |
| Knowledge | Vocabulary and general information built up through learning and experience |
| Quantitative reasoning | Working with numbers, quantities and number problems |
| Visual-spatial processing | Seeing patterns and relationships between shapes — see spatial reasoning |
| Working memory | Holding and rearranging information for a few seconds — see working memory |
Testing starts with two routing subtests, one nonverbal reasoning task and one vocabulary task. Their results tell the examiner where to start in the rest of the test, so that nobody spends long on items far too easy or far too hard, and together they give a short screening estimate called the Abbreviated Battery IQ.
How the Stanford-Binet is scored
Raw answers are converted into scores that compare the person with a norm sample of the same age. For the SB5 that sample was about 4,800 people, chosen to match the US population by age, sex, ethnicity, region and socioeconomic level. The main scores are:
- Full Scale IQ — the overall score, from all ten subtests;
- Verbal IQ and Nonverbal IQ — one from each domain;
- five factor index scores — one per factor;
- Abbreviated Battery IQ — the quick estimate from the two routing subtests.
The IQ and index scores have an average of 100 and a standard deviation of 15, the same scale as most modern tests:
| SB5 score | Higher than about |
|---|---|
| 85 | 16% of the same age group |
| 100 | 50% (the average) |
| 115 | 84% |
| 130 | 98% |
| 145 | 99.9% |
Our IQ percentile calculator converts any score on this scale, and our guide to what counts as a good IQ explains the ranges.
Does it really measure five separate abilities?
The test’s own manual supports the five-factor design, but independent researchers have been more cautious. Gary Canivez re-analysed the SB5 standardization data for children and adolescents in 2008. Every criterion he used supported only one dimension, and the largest share of the variance belonged to the general factor, the g factor. He found no evidence for a five-factor solution and concluded that interpretation should focus “primarily, if not exclusively” on the Full Scale IQ.
In practice this means the overall IQ is the most dependable number an SB5 report contains. A factor profile can still prompt useful questions, but a gap between two index scores is weaker evidence than the Full Scale IQ, and it should be read by the psychologist in the light of everything else they know about the person.
Who takes the Stanford-Binet, and why
Because one edition spans early childhood to old age and includes nonverbal subtests, the SB5 is used widely with young children and in schools. Typical reasons are an assessment for a gifted or advanced program, an assessment of a suspected developmental delay or learning difficulty, or eligibility for special education services. The test is also used with adults. The full battery usually takes about 45 to 75 minutes. For children, our guide to IQ tests for kids covers how a school or private assessment works.
Can you take the Stanford-Binet test online?
No. The SB5 is given face to face by a trained examiner using a kit of test materials and record forms, and the examiner adapts where to start and stop from the person’s answers. It has no official version that you take on your own. Websites that offer a “Stanford-Binet test” online — free or paid — are not the published test: their questions, scoring and norms do not come from it, so their result is not a Stanford-Binet IQ, whatever it is called.
The IQ Revealed test is an online reasoning test of 40 original items. It is not the Stanford-Binet, uses none of its items and is not normed against it, and its result should never be read as a Stanford-Binet score. Our guides to how IQ tests work and how accurate IQ tests are explain what an online test can and cannot tell you.
Trust and scope notes
This page explains a psychological test in general terms. The Stanford-Binet is used within clinical and educational assessments; only a qualified professional can administer and interpret it for an individual, and nothing on this page, or our own test, can stand in for that or for a diagnosis. Our IQ test is for adults aged 18 and over.
IQ Revealed is not affiliated with, endorsed by or connected to the publishers of the Stanford-Binet Intelligence Scales, Stanford University, the publishers of the Wechsler scales, or the researchers and universities named on this page. “Stanford-Binet” and the other test names are used only to identify the tests being described.