What's Your IQ

From a French scale to an American number

1905Binet-SimonThe French scale appears. Edmund Huey of Johns Hopkins urges Terman to take it up for America.¹

1910StanfordTerman joins the Stanford faculty, starting as an assistant professor in education.²

1911An early studyHe uses the Binet-Simon scale to select 31 children with IQs over 125 for study.¹

1912Stern's quotientWilliam Stern proposes dividing mental age by chronological age.⁴

1916The Stanford revisionTerman publishes the revision, scales the quotient by 100 and becomes a full professor.¹

EXPLORE · THE RATIO IQ, AND WHERE IT BREAKS

Set two ages and read the quotient

On the scale, average mental age climbs quickly in childhood, then more slowly, and levels off a little before 16.¹ Real age keeps rising, so the ratio drifts downward for adults. That's one reason it was replaced by the deviation IQ from 1939.⁴

Mental age12 yrs

Chronological age10 yrs

12 ÷ 10 × 100120ratio IQ

Mental age at or above real age: the child is doing what an older child typically does.

THE SCALE'S REACHThe standard for decadesTerman kept revising the scale, and it became the standard for fixing children's IQs and, to a lesser degree, adults'. It has been revised five times since 1916, most recently in 2003.¹

HEREDITYIntelligence as innateTerman believed heredity, not environment, explained high intelligence, and advocated tests as measures of innate ability.⁶

THE ARMYFrom one child to two millionWhen the US entered the war in 1917, a committee that included Terman helped develop the group Army Alpha and Beta for recruits.⁵

References

[1]Terman, Lewis M. International Encyclopedia of the Social Sciences. Encyclopedia.com.encyclopedia.com

[2]Lewis Terman. Encyclopaedia Britannica.britannica.com

[3]Wikipedia contributors. Lewis Terman (accessed 1 Oct 2026).en.wikipedia.org

[4]Ratio IQ: the original IQ formula (MA ÷ CA × 100). Cogn-IQ encyclopedia (2026).cogn-iq.org

[5]The intelligence test that started it all: Stanford-Binet's unlikely origin story. stanford-binet.org (2026).stanford-binet.org

[6]Lewis Terman: theory and contribution. Vaia.vaia.com

HOW TO CITE THIS PAGE

What's Your IQ. (2026). Stanford-Binet (1916). In Historical IQ Tests Archive. Retrieved October 1, 2026, from /en/historical-iq-tests/stanford-binet-1916

EDITORIAL RECORD

First published2026

Last reviewed1 October 2026

Sources6: encyclopedia entries and histories of the IQ

Open questionsThe 1916 item count and the size of Terman's standardisation sample

Canonical URLwhats-your-iq.com/en/historical-iq-tests/stanford-binet-1916

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Goddard's translation was the American Binet before 1916. Terman's revision, with its IQ, displaced it within a few years.

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The next revision1937

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Terman and Maud Merrill's 1937 revision added parallel forms L and M. It was still scored as a ratio IQ.

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Wechsler's 1939 scale compared adults with their own age group instead of using a ratio, the deviation IQ that every modern test now uses.

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Part of the Historical IQ Tests Archive. Editorial content under CC BY-SA 4.0. Terman's 1916 book is in the public domain.

BibTeX RIS

Mental age ÷ real age × 100.

From a French scale to an American number

Set two ages and read the quotient

References

Related historical tests

Terman set 100 as average. Adults now get a fairer ruler.