IQ Scale Chart: Every Range, Level and Percentile Explained

The IQ chart

The IQ scale chart: seven levels from Extremely Low to Very Superior

The IQ scale is a standard score: mean 100, standard deviation 15.¹ The Wechsler tests divide it into seven IQ levels, each with its own score range. Extremely Low is 69 and below, Borderline 70 to 79, Low Average 80 to 89, Average 90 to 109, High Average 110 to 119, Superior 120 to 129 and Very Superior 130 and above. Half of all people score between 90 and 109.

The IQ ranges are conventions, not cliffs. A 129 and a 131 are the same performance wearing different labels, which is why a clinical report always prints a confidence band around the number.² The share column comes from the normal curve the scale is built on, so it is symmetrical: 2.2% at each end, 6.7% in each of the next two levels, 16.1% in each of the two beside the middle.

Two thirds of people sit within one step of the centre, 85 to 115. Nineteen in twenty sit within two steps, 70 to 130. Beyond that the curve thins so fast that each further point removes a shrinking slice of the population, which is the single most useful thing to know before reading any high score.

Reading a level

What counts as a normal, good, high or genius IQ

The words people search for are not the words on the IQ chart, so here is the translation, one IQ level at a time.

A normal IQ

Normal is 90 to 109, the Average level, and it holds half of everyone. Widen it to 85 to 115 and it holds 68%. A report that says 96 or 104 is describing the middle of the population, not a strength or a weakness. Nor is an 88 a verdict: it sits at the 21st percentile, one person in five, and its error band reaches well into Average. The average IQ is 100 by definition on every modern test, because each test is normed to make it so.⁴

A good IQ

There is no official cutoff for good. Above 110 you have outscored three in four people. Above 120 you have outscored ten in eleven. The more honest question is good for what. The High Average level is common among university graduates and people in knowledge work, but most jobs are done well across a wide stretch of the scale, and conscientiousness, sleep and experience move outcomes at least as much as fifteen points do. Psychologists who give these tests tend to put it more plainly: an average score is a good score, because it is the score that does almost everything most people need to do.

A high IQ

High usually means 120 and above, the Superior level, which is the top 9%. Very Superior begins at 130, the top 2%, and that is the line most gifted programmes and every Mensa chapter use. Mensa accepts 130 on a WAIS or Stanford-Binet 5, 132 on an older SD 16 Stanford-Binet and 148 on the Cattell scale, all of which mark the same 98th percentile.⁵ Some school districts admit gifted pupils at 125 or the 97th percentile instead.

A genius IQ

No test defines genius. Terman's original 1916 Stanford-Binet table labelled 140 and above "near genius or genius", and the word has stuck to that number ever since.⁶ On today's scale 140 is the 99.6th percentile, 145 is about 1 in 740, and 160, the ceiling of most tests, is about 1 in 31,000. Above 145 the instruments run out of hard items and norm cases, so the numbers get noisier exactly where the claims get bolder. Charts that stack extra tiers at 140, 160 and 180 with tidy population shares are decorating the tail of a curve no test can measure that finely.

Low scores and intellectual disability

A score of about 70 or below, two standard deviations under the mean, is one of two criteria for intellectual disability. The other is difficulty with everyday adaptive skills such as managing money, communication and self-care, and the DSM-5-TR grades severity by adaptive functioning rather than by the IQ number alone, although the older bands (mild 50 to 69, moderate 35 to 49, severe 20 to 34, profound below 20) still appear in reports.¹⁰ About 2.2% of scores fall below 70; not all of the people behind them meet the second criterion.

Precision

What one IQ score can and cannot tell you

Every score on the chart carries error. Full Scale IQ on the WAIS-IV is among the most reliable measures in psychology, with internal consistency between .97 and .98 across all thirteen age groups.¹³ Even that leaves a standard error of measurement near two and a half points, which puts the 95% confidence interval about five points either side. A 120 is best imagined as 115 to 125. A short online test is wider still, around ten points either side, and online scores, ours included, tend to run higher than a supervised test would give the same person, because the norms are drawn from web samples rather than a census-matched one.

Three other things sit outside the number. First, the profile: two people with the same Full Scale IQ can have opposite strengths across verbal, spatial, memory and speed indices, and for most practical questions the profile matters more than the total. Second, time: measured performance has risen about three points a decade across the twentieth century, the Flynn effect, which is why tests are re-normed and why a 1995 score and a 2025 score with the same number rest on different comparison groups.⁸ Third, the day: sleep, anxiety, illness, a second language and a noisy room all move a sitting by more than the difference between two neighbouring levels.

Questions

IQ scale questions people ask