IQ reference chart

IQ reference charts are tables suggested by IQ test publishers to designate IQ score ranges as various categories. As reference charts, they are not to be taken as absolute or precise. All IQ tests show variance in scores even for the same test-taker retested on the same test, and also variance in scores among IQ tests from different publishers. Category labels for IQ score ranges are specific to each brand of test and are arbitrary.

Terman classification

Lewis Terman, developer of the Stanford-Binet intelligence test, chose the category ranges for score levels on that test using a standard deviation of 16.

Terman's Stanford-Binet Fourth Revision classification

IQ Range ("Deviation IQ")	Intelligence Classification
152 and over	Genius and near genius
148 - 151	Very superior intelligence
132 - 148	Superior intelligence
116 - 132	Above average intelligence
84 - 116	Normal or average intelligence
68 - 84	Dullness
52 - 68	Borderline deficiency
Below 52	Mental Deficiency

Wechsler classification

The Wechsler Intelligence Scale for Children uses the following category labels, the scores are scaled with a standard deviation of 15.

Wechsler's classification

IQ Range ("Deviation IQ")	Intelligence Classification
>= 130	Very superior
120 - 129	Superior
110 - 119	High Average
90 - 109	Average
80 - 89	Low Average
70 - 79	Borderline
<= 69	Extremely Low

See also

• Intelligence quotient
• Level of measurement: Ordinal scale
• Intellectual giftedness
• Mental retardation
• Stanford-Binet Intelligence Scales
• Wechsler Adult Intelligence Scale

Bibliography

• Kaufman, Alan S. (2009). IQ Testing 101. New York: Springer Publishing. pp. 151–153. ISBN 978-0-8261-0629-2. 
• Wechsler, David (1958). The Measurement and Appraisal of Adult Intelligence (fourth ed.). Baltimore (MD): Williams & Witkins. Chapter 3.