The Stanford-Binet Test: What It Measures and How It Scores

From Paris to Stanford

Alfred Binet and Theodore Simon published the first practical intelligence test in Paris in 1905, to identify schoolchildren who needed extra help. Lewis Terman of Stanford University adapted it for American use in 1916, and the Stanford revision gave the test its name. Terman and Maud Merrill revised it in 1937. Merrill's 1960 Form L-M introduced the deviation IQ, with a mean of 100 and a standard deviation of 16, and was renormed in 1973.

Robert Thorndike, Elizabeth Hagen and Jerome Sattler produced the fourth edition in 1986. Gale Roid's fifth edition, the SB5, followed in 2003 from Riverside Publishing of Itasca, Illinois. The test is now sold by PRO-ED of Austin, Texas, which also runs its online scoring system. The full lineage is traced in our history of the IQ test.

Five Factors, Two Domains

The SB5 crosses five cognitive factors with two domains, verbal and nonverbal, for ten subtests. Each subtest is built from short sets of activities that rise in difficulty. Nonverbal subtests let a child or adult respond by pointing or by arranging pieces, which reduces the weight of spoken language. Activity names below come from the published test structure; items are confidential.

The two routing subtests come first. The examinee's results on Object Series/Matrices and Vocabulary set the starting level for the remaining nonverbal and verbal subtests, so a gifted ten-year-old and a struggling one begin at different points. That adaptive design keeps sessions shorter and reduces time spent on items that are far too easy or far too hard.

The Scores on an SB5 Report

Each subtest yields a scaled score with a mean of 10 and a standard deviation of 3. Composites use a mean of 100 and a standard deviation of 15, the same metric as the Wechsler tests. The SB5 reports four IQs and five factor indexes:

• Full Scale IQ (FSIQ): all ten subtests.
• Nonverbal IQ and Verbal IQ: five subtests each.
• Abbreviated Battery IQ (ABIQ): the two routing subtests alone, used for screening.
• Factor indexes: Fluid Reasoning, Knowledge, Quantitative Reasoning, Visual-Spatial and Working Memory, each combining one verbal and one nonverbal subtest.

Reports also give percentile ranks, confidence intervals, age equivalents and change-sensitive scores, which track growth on an absolute scale across repeated testing. Reliability is high. In Roid and Barram's 2004 guide to the test, the FSIQ averaged .98 with a standard error of measurement of 2.30 points; the two-subtest ABIQ averaged .91.

How the SB5 Labels Scores

The SB5 uses more categories at the top than the Wechsler tests, and it names giftedness outright.

Shares are theoretical normal-curve figures, not counts from the norm sample. An SB5 score of 145, the start of the top band, is matched by about 1 person in 740; our page on an IQ of 145 shows the arithmetic. For side-by-side labels from other tests, see the IQ classification chart.

Why Gifted Programs Use It

The SB5 was designed with high-end items aimed at assessing intellectual giftedness, and its Extended IQ option goes far beyond the standard 40 to 160 composite range. Roid and Barram describe the Extended IQ as measuring IQ down to 10 and up to 225. That is a statistical extrapolation for rare cases, not a claim that the norm sample contained people at 225. It does give examiners a way to describe a result at the very top of the standard range.

The test reaches down as well as up. Its age range starts at 2, its labels run to Moderately impaired or delayed, and the Extended IQ also extends below 40, so the same instrument can serve a gifted referral and a developmental one. For what high scores look like in context, see what counts as a high IQ.

Retesting and Practice Effects

Repeat testing raises scores modestly. Roid and Barram reported nonverbal IQ shifts of only 2 to 5 points when examinees were retested 5 to 8 days apart. Sbordone, Saul and Purisch, in a 2007 neuropsychology text cited by Ray, put typical FSIQ improvements at 2 to 4 points. Christopher Ray's 2009 review noted that the SB5 may be repeated sooner than most intelligence tests but advised waiting at least six months.

The practical rule for parents and adults: two scores taken weeks apart are not independent evidence. If the numbers differ by a few points, measurement error and familiarity explain it.

Who Gives It and What It Costs

The SB5 is administered one-to-one by a trained examiner, typically a school, clinical or educational psychologist. PRO-ED notes that a trained adult must closely supervise children's use of the manipulatives. The complete test kit, with examiner's and technical manuals, three item books, 25 record forms and manipulatives, listed at $1,353 on PRO-ED's site in October 2026. Fees for an evaluation are set by the examiner.

No online test reproduces the Stanford-Binet, whatever its name. The free geniuses.club IQ test is a practice screener, and our guide to online IQ test accuracy explains why. Compare the SB5 with the Wechsler family in our WISC-V guide and our WAIS-IV guide, or browse every explainer in the IQ guides. When the examinee is a child, a licensed psychologist interprets these scores.

Editorial standard: IQ figures for historical figures are retrospective estimates and are labeled as such; scores for living people appear only when the person disclosed them or a reputable outlet reported them. Corrections: contact the editors.