What Does an IQ of 155 Mean?

An IQ of 155 is at the 99.988th percentile: it is higher than about 99.988% of people of the same age, and about 1 in 8,140 people scores 155 or higher. On the WAIS-IV it is classed as Very Superior. Like every IQ score it is an estimate with a margin of error of several points, and it predicts outcomes only on average.

IQ 155 percentile and how it is calculated

IQ tests are scaled so that scores follow an approximately normal distribution with a mean of 100 and a standard deviation (SD) of 15. A score of 155 is 3.67 standard deviations above the mean (z = +3.667). Plugging that into the normal cumulative distribution function gives a percentile of 99.988. Put simply: in a representative group of 1,000 people of your age, about 0 would score 155 or higher.

Some reports use a slightly different convention — for example the percentage of people scoring strictly below 155, or a value read from the test’s own norm tables rather than the ideal curve — so you may see a percentile a fraction of a point different. The full list for every score from 55 to 160 is in our IQ percentile chart.

How 155 compares with nearby scores

Is 155 a good IQ score?

It is extremely rare (about 1 in 8,000), and few tests can measure it reliably. See also what counts as a good IQ score.

How rare is a 155 IQ?

On the normal model, about 1 in 8,140 people scores 155 or higher. That is about 123 per million people, or roughly 6,100 people in a country of 50 million. Rarity grows quickly in the tails: each extra 5 points above 100 multiplies the rarity, which is why the step from 155 to 160 (1 in 8,140 → 1 in 31,570) is much bigger than the step from 150 to 155.

155 IQ classification

Different tests use different descriptive words for the same number. For a full-scale score of 155:

These labels describe where a score falls relative to peers; they are not diagnoses. Newer reports, such as the WAIS-5 sample report, use plainer wording (“Average”, “Above average”, “Very high”). See all bands in IQ score ranges and classification.

What an IQ of 155 means in practice

155 is about 3.67 standard deviations above the mean, roughly the 99.99th percentile — about one person in 8,100. In a city of one million people you would expect around 120 residents at or above this level.

Very few tests can measure this level reliably. Standard Wechsler norms end at 160, and norm samples of a few thousand people contain almost nobody this high, so the score depends on how the publisher extended the normal curve. Two respected tests can disagree by 10 points or more for the same individual at this level.

If you received a 155 on a supervised, individually administered test, the practical message is less about the number and more about fit: profoundly gifted learners often benefit from acceleration and specialist guidance, and adults may find it useful to seek out work and communities with enough complexity and autonomy.

155 IQ jobs, education and life outcomes: what research says

Large meta-analyses agree that IQ predicts educational and occupational outcomes on average, with plenty of individual exceptions. Strenze (2007), pooling longitudinal studies, found corrected correlations of about .56 between intelligence and education, .43 with occupational level and .20 with income. For job performance, Schmidt and Hunter (1998) estimated a validity of about .51 for general mental ability; a 2022 re-analysis by Sackett and colleagues revised it to about .31, still useful but leaving most differences in performance to other factors such as experience, conscientiousness and job knowledge.

How does 155 look against real occupations? The table uses Wolfram’s (2023) estimates from the UK Understanding Society survey and assumes a typical spread of about 13 points inside each occupation (the study found only about a quarter of IQ variance lies between occupations). It shows how many people in each group would be expected to score below 155 — a reminder of how much occupations overlap.

Read more in average IQ by occupation. These are group estimates from a short test battery, not entry requirements.

Measurement error: how precise is a score of 155?

A full-length clinical test such as the WAIS-IV or WAIS-5 has very high reliability (internal consistency around .97–.98 for the full-scale IQ), which still leaves a standard error of measurement (SEM) of about 2–3 points; Pearson’s WAIS-5 sample report lists an FSIQ SEM of 3.00. A 95% confidence interval is roughly ±1.96 SEM, so a measured 155 is best read as about 149 to 161. Shorter tests have larger errors (SEM 4–5 or more), widening the band to roughly 146–164.

Extreme scores also tend to move toward the mean on re-testing (regression to the mean). With a reliability of .96, the best estimate of the “true” score behind an observed 155 is about 152.8, which is why many reports centre the confidence interval slightly below the obtained score.

What an IQ of 155 does not tell you

• Index scores (verbal, spatial, reasoning, memory, speed) can differ widely behind the same full-scale number.
• It does not fix the future: correlations of .2 to .6 leave room for very different outcomes among people with the same score.
• It cannot be compared across very different tests or eras without adjusting for norms.
• It does not measure creativity, practical wisdom, emotional skills, motivation or character.
• It is a sample of performance on one day; sleep, stress, language and familiarity with tests all affect it.

The Flynn effect and old norms

A score of 155 also depends on when the test was normed. During the 20th century, average performance on IQ tests rose by about 3 points per decade (Pietschnig & Voracek, 2015; Trahan et al., 2014), so publishers periodically re-norm. Using norms that are 20 years out of date could add roughly 6 points, turning a current-norm 149 into a reported 155.

Online IQ tests and a score of 155

Most online IQ tests are not normed on a representative sample, are taken unsupervised, often have no time control and are completed by a self-selected audience. Many also inflate results to encourage sharing or paid certificates. Treat an online 155 as a rough hint at best; see how accurate online IQ tests are.

How to get a proper IQ assessment

A valid IQ score comes from an individually administered, standardized test (for example the WAIS-5/WAIS-IV for adults, WISC-V for children, or Stanford-Binet 5) given by a licensed or registered psychologist. Expect 60–120 minutes of testing, a written report with index scores and confidence intervals, and a fee that varies by country and provider. Schools, university disability services, and clinical or neuropsychology services can refer you. Ask which test and which norms were used, and for the confidence interval, not just the single number.