IQ Classification Chart

This IQ classification chart shows the standard score ranges used on Wechsler scales, such as average (90-109) and very high (120-129), together with the theoretical share of people in each. Enter a score to see its band. About half of all people score between 90 and 109, and about 2.3 percent score 130 or above. The labels describe position on a curve, not a diagnosis.

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IQ score

Test scale (standard deviation)

How to use the IQ Classification Chart

Enter your IQ score and its scale.
Press Calculate to see the band and where it sits in the table.
Compare with the table of bands and their theoretical shares of the population.
Read the guidance on what the labels do and do not mean.

Formula and method

Shares come from the normal curve with mean 100 and SD 15: share = Phi((upper - 100)/15) - Phi((lower - 100)/15). For average (90-109), z runs from -0.667 to +0.667, giving 49.5%. For 130 and above, z >= 2.00 gives 2.28%.

IQ classification chart (Wechsler descriptors, SD 15)

IQ range	Label	Theoretical share
130 and above	Extremely high	2.28%
120-129	Very high	6.85%
110-119	High average	16.13%
90-109	Average	49.50%
80-89	Low average	16.13%
70-79	Very low	6.85%
69 and below	Extremely low	2.28%

Percentages use continuous band edges at 70, 80, 90, 110, 120 and 130. Published manuals may list slightly different empirical shares.

Bands are labels, not diagnoses

Descriptors such as extremely low or very high only tell you where a score sits on a distribution. A clinical conclusion, such as identifying an intellectual disability or eligibility for a gifted program, needs a full evaluation that also considers adaptive functioning, background and other evidence. Different tests and schools use different cutoffs.

Names have changed over time

Older classifications used terms such as genius, moron or imbecile. These are now considered offensive and inaccurate. Current Wechsler manuals use neutral descriptors, and terms such as superior or borderline appear in some editions. The Wikipedia article on IQ classification lists historical schemes.

How the same score is classed on other scales

On SD 16 and SD 24 scales the cutoffs move. Two thirds of people fall within one SD of the mean, which spans 84 to 116 on SD 16 and 76 to 124 on SD 24. Use the calculator above, which converts everything to SD 15 before classifying.

Limits and responsible use

Important: this is a statistics tool, not an IQ test. It converts a score you already have into a percentile and a descriptive band using a normal (bell-curve) model. Clinical IQ scores come only from a standardized test given and interpreted by a qualified psychologist, and online quizzes give estimates at best.

Frequently asked questions

What is an average IQ range?

90 to 109 on Wechsler scales, which includes about half of the population.

What IQ is considered high?

Wechsler descriptors call 110-119 high average, 120-129 very high and 130 and above extremely high.

What IQ is considered low?

80-89 is low average, 70-79 very low and below 70 extremely low. These are labels, not diagnoses.

Is 120 a good IQ?

It is at about the 91st percentile on SD 15, higher than roughly 9 out of 10 people.

What IQ is gifted?

There is no single standard. Programs often use cutoffs between 120 and 135 or a percentile, and decisions rely on more than one measure.

How many people have an IQ above 130?

About 2.3 percent in theory, about 1 in 44.

Sources

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