The short answer
The Stanford-Binet Intelligence Scales are individually administered tests of intelligence for ages 2 to 85 and over. The current edition is the Fifth Edition (SB5, 2003), published by Riverside, with scores on a scale of mean 100 and standard deviation 15.
The test grew out of the Binet-Simon scale of 1905, and Lewis Terman at Stanford revised it in 1916. Older editions used a standard deviation of 16, which is why the same level of ability is a 132 on the older scale and a 130 on the current one.
- Current edition
- Stanford-Binet Fifth Edition (SB5), 2003, by Gale Roid
- Publisher
- Riverside (Riverside Insights)
- Age range
- 2 to 85 and over
- Factors
- Fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing and working memory, each in verbal and nonverbal form
- Scale
- Mean 100, SD 15 (older editions SD 16)
- Administration
- One-to-one by a qualified examiner
From Binet and Simon to the SB5
Alfred Binet and Théodore Simon designed their scale in France in 1905 to identify children who needed extra help at school. Lewis Terman at Stanford adapted it for American use in 1916, and that Stanford Revision popularised the idea of an intelligence quotient.
| Year | Edition | What changed |
|---|---|---|
| 1905 | Binet-Simon scale | A set of tasks ordered by difficulty to find children needing support |
| 1916 | Stanford Revision (Terman) | Adapted for the US; IQ reported as mental age over chronological age |
| 1937 | Forms L and M | Two parallel forms, extended age range |
| 1960 | Form L-M revision | Ratio IQ replaced by deviation IQ, with a standard deviation of 16 |
| 1986 | Fourth Edition | Adaptive testing with point scales; SD 16 |
| 2003 | Fifth Edition (SB5) | Five factors, verbal and nonverbal; SD 15 |
The original ratio IQ, and why it was dropped
In the early editions, IQ was literally a ratio: mental age divided by chronological age, multiplied by 100. A 10-year-old who performed like a typical 12-year-old had an IQ of 12 ÷ 10 × 100 = 120.
The ratio worked for children and failed for adults, because mental age stops rising in adulthood, so the formula would drop the IQ of everyone as they got older. Later editions replaced it with a deviation IQ, which compares a person with others of the same age and sets the average at 100 by definition. That is the approach every modern IQ test uses.
Standard deviation 16, and how to convert old scores
The Stanford-Binet editions from 1960 to 1986 defined the spread of scores with a standard deviation of 16 points. The SB5 uses 15, like the Wechsler tests. A score of 116 on the older scale is one standard deviation above average, and so is 115 on the newer one.
That is why American Mensa lists 132 for the old Stanford-Binet and 130 for the SB5. Both are two standard deviations above average. To convert an older score to the 15-point scale, subtract 100, multiply by 15/16, and add 100 back.
| Old scale (SD 16) | Standard scale (SD 15) | Percentile |
|---|---|---|
| 100 | 100 | 50th |
| 116 | 115 | 84th |
| 132 | 130 | 97.7th |
| 148 | 145 | 99.9th |
| 164 | 160 | 99.997th |
Why an "online Stanford-Binet" is not the test
The SB5 is an individually administered test with printed materials and a trained examiner who records responses. It is not offered as a self-service website test to the public. Sites that advertise the "only accredited online Stanford-Binet" or similar claim a link to the test that we could not verify, and their scores have no connection to the publisher's norms.
If you need a genuine result, for a school, a diagnosis or a society, find a psychologist who is qualified to give the SB5 or another test such as the WAIS. If you only want a rough look at your reasoning, a free online test is fine, as long as you treat the number as an estimate.
Try nonverbal reasoning items
The SB5 includes a nonverbal fluid reasoning factor, which uses pattern and matrix tasks. Here are three original items in that spirit.
Question 1
Warm-upWhich option completes the grid?
Worked solution
Every shape is red, so colour is a distraction. The number of shapes grows by one across each row: one, two, three. The shape itself is fixed by the row. The bottom row is squares, so the missing cell holds three squares.
Question 2
EasyWhich option completes the grid?
Worked solution
Two rules run at once. Down the columns the shape stays the same (hexagon, triangle, circle). Down the rows the size increases: small, then medium, then large. The missing cell is in the third column (circle) and the third row (large), so it is a large blue circle. Every shape is blue, so colour carries no information.
Question 3
MediumWhich option completes the grid?
Worked solution
The shape is fixed by the row: squares, diamonds, hexagons. The colours form a Latin square, meaning blue, red and yellow each appear exactly once in every row and every column. The bottom row already contains yellow and blue, and the last column already contains yellow and blue, so the only colour left for the missing cell is red. The answer is a red hexagon.
Your practice score
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0 of 3 answered. Finish them all to see your score.
25 questions, 12 minutes. Free to take. Your score and full report are a paid unlock once you finish.
Stanford-Binet: frequently asked questions
Can I take the Stanford-Binet test online?+
Not as the real test. The SB5 is given one-to-one by a qualified examiner. Websites that offer an "online Stanford-Binet" are not the publisher's test and have no official norms.
What is a good Stanford-Binet score?+
On the SB5 the average is 100 with a standard deviation of 15. A score of 130 or above is in about the top 2%. On older editions the standard deviation was 16, so 132 is the equivalent.
What is the difference between the Stanford-Binet and the WAIS?+
Both are individually administered IQ tests with a standard deviation of 15 in current editions. The SB5 covers ages 2 to 85 and over with five factors, and the WAIS is for ages 16 to 90 with five indexes. They give similar but not identical scores.
Does Mensa accept the Stanford-Binet?+
Yes. American Mensa accepts an IQ of 130 on the SB5 and 132 on the older edition, from a psychologist-administered test.
Who invented the Stanford-Binet?+
Alfred Binet and Théodore Simon created the original scale in 1905. Lewis Terman at Stanford University adapted it in 1916, and later revisions led to the current fifth edition.
Why was the old Stanford-Binet standard deviation 16?+
Editions from the 1960 revision to the fourth edition used a deviation IQ with a spread of 16 points. The fifth edition changed to 15 to match the Wechsler tests.
More on IQ tests
- WAISThe WAIS is the gold-standard adult IQ test, and it cannot be taken by yourself online.
- Cattell Culture Fair testThe Cattell Culture Fair test was built to measure reasoning without leaning on language.
- Raven's Progressive MatricesRaven's Progressive Matrices is one of the most widely used non-verbal reasoning tests in the world.
- Mensa practice testMost "Mensa tests" online are not Mensa tests, and none of them can get you in.
- IQ test questions and answersReal IQ test questions are secret, so this page does the next best thing: original questions of every major type, with answers and a short explanation of the rule behind each.
- All named IQ testsCompare the tests side by side.
- Test score to IQ convertersTurn an SAT, ACT, GRE or other score into an estimated IQ.
- Mensa eligibility checkerCheck what a score means across different IQ scales.
References & Sources
Wikipedia contributors (2026). Stanford-Binet Intelligence Scales. Wikipedia. https://en.wikipedia.org/wiki/Stanford%E2%80%93Binet_Intelligence_Scales
American Mensa (2026). Qualifying test scores. us.mensa.org. https://www.us.mensa.org/join/testscores/qualifying-test-scores/
Riverside Insights (2003). Stanford-Binet Intelligence Scales, Fifth Edition. Riverside Publishing.
Stanford-Binet is a trademark of its owners. LifeScore is not affiliated with the publisher, and this page is independent commentary. Practice items are original.