Stanford-Binet IQ Test: What the SB5 Measures and How It Compares

What does the SB5 measure?

The SB5 measures five abilities: fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing and working memory. PAR lists these five factors across the 10 subtests.

• Fluid reasoning: solving new problems without relying on facts you learned.
• Knowledge: the words and facts you have picked up at school and elsewhere.
• Quantitative reasoning: working with numbers and quantities.
• Visual-spatial processing: seeing how shapes fit together and relate.
• Working memory: holding information in mind while you use it.

The SB5 reports a Full Scale IQ, a Nonverbal IQ and a Verbal IQ, plus five factor indexes (PAR). Composite scores have a mean of 100 and a standard deviation of 15, and each subtest has a mean of 10 and a standard deviation of 3 (Roid and Barram).

PAR lists 5 minutes per subtest. Ten subtests therefore add up to roughly 50 minutes of testing, before setup and scoring.

Can you take the Stanford-Binet online?

No, the real SB5 cannot be taken alone online, because an examiner with professional credentials has to give it.

The SB5 kit is listed at qualification level C. To buy a level B or C test, PRO-ED requires a User Acceptance Form with the buyer’s training and professional credentials. PAR lists the complete kit at $1,353 and the combination kit with online scoring at $1,453. The online part is the scoring, which PRO-ED’s catalogue lists as a separate $248 first-year subscription. The testing happens with an examiner.

Independent sites that use the name sell something different. stanford-binet.org describes itself as an independent online assessment, not affiliated with Stanford University and not administered by a clinician, at $69 for one assessment. The SB5 publisher is PRO-ED, so this is a separate business.

Three questions sort any site that uses the name. Who published the test? Who gives it? What group of people were the scores compared with? A genuine SB5 answer is PRO-ED, a qualified examiner and 4,800 people matched to US Census statistics. A site that cannot answer all three offers an online estimate, and an estimate that says so plainly is a fine tool.

How does the Stanford-Binet compare with the WAIS and an online estimate?

The SB5 and WAIS-5 are examiner-given, while an online estimate is self-given, shorter and narrower.

Read the table as a map of different jobs. The SB5 and the Wechsler tests give a profile across several abilities and cover young children or whole age ranges. The SB5 starts at age 2, while Pearson lists the WAIS-5 for ages 16 through 90 (Pearson). A 20-puzzle estimate covers one skill, once, in about 10 minutes.

How do the SB5 and WAIS-5 publication dates compare?

The SB5 carries a 2003 copyright and the WAIS-5 a 2024 publication date, so the two editions were published 21 years apart.

Publication dates matter because average scores on a fixed test drift upward as norms age. A meta-analysis of 285 studies (14,031 people) found that scores rise about 2.31 points per decade overall. For 53 comparisons of modern Stanford-Binet and Wechsler tests, dated since 1972, the rate was 2.93 points per decade (Trahan et al., 2014). That is the reason publishers renew norms, and the reason to check which edition produced a score.

Why does Mensa accept 132 on one Stanford-Binet and 130 on another?

Mensa’s 132 and 130 mark the same point on the curve, two standard deviations above average, because the older scale had a standard deviation of 16 and the SB5 has 15.

American Mensa lists 132 for the Stanford-Binet, 130 for the Stanford-Binet 5, 130 for the Wechsler editions it names (WAIS through WAIS-IV, WISC through WISC-V, WPPSI) and 148 for the Cattell. The list does not name the WAIS-5. Mensa Italia gives the standard deviation behind each: Wechsler 15, Stanford-Binet 16, Cattell 24, and Roid and Barram’s guide confirms the SB5 uses 15. Mean 100 plus two standard deviations gives 130, 132 and 148.

The size of a point changes the meaning of a number. A 132 on a scale with a standard deviation of 16 sits exactly 2.0 standard deviations above average, the 97.7th percentile. A 132 on a scale with a standard deviation of 15 sits 2.13 above, the 98.4th percentile (our arithmetic on the normal curve). That is why the older scale needs 132 to reach the spot where the SB5 needs 130.

IQMog reports on a scale with a mean of 100 and a standard deviation of 15 (How IQMog scores). As an illustration, 14 of 20 correct gives 70 + 3 × 14 = 112, with a likely range of roughly 100 to 124. Use IQMog to see where you stand before you book a supervised Mensa test; the page on Mensa score requirements lists the accepted tests.

How high can a Stanford-Binet score go?

The SB5 Full Scale IQ runs from 40 to 160, and its Extended IQ scale reaches beyond both ends. The publisher’s examples are scores as low as 10 and as high as 225 (PRO-ED catalogue; Roid and Barram).

You will see claims that every real test stops at 160. For the SB5 the Extended IQ scale says otherwise. Scores that high are rare in practice, and the curve shows why. A score of 160 is 4 standard deviations above 100 on a scale with a standard deviation of 15. A normal curve puts about 1 person in 31,500 that high. A norm sample of 4,800 people is expected to hold about 0.15 of such a person, which is fewer than one (our arithmetic: 4,800 ÷ 31,500).

With so few people near the top of any sample, extremely high scores carry more uncertainty than scores near 100. Mensa does not need them either: its line is 130, so the part of the scale that matters for membership sits well inside the ordinary range.

Labels for score bands differ by test, so check which test a label refers to. The IQ classification bands page lists the common ones. IQMog’s 20-item form shows scores from 70 to 130, the range where most people land. The SB5 Full Scale IQ covers 40 to 160, and its Extended IQ reaches beyond those limits.

How do you get a Stanford-Binet assessment?

You book an assessment with a psychologist or school psychologist who is qualified to give the SB5.

PRO-ED makes buyers show their training and credentials first, so the office has to hold the SB5 before it can give it. The office may use the SB5, a Wechsler test or another instrument, so ask which one before you book. Ask what the report will include and whether it gives the full scale score you need. If you want the score for Mensa, check the exact name and edition of the test against the Mensa list in the previous section.

For school placement, a diagnosis or a job decision, book the formal assessment. For a quick read on one skill, the online estimate is the right tool, as how accurate online IQ tests are explains.