IQ 59
What does an IQ of 59 mean?
59 is near three standard deviations below the mean. Here is what the number means on the scale, and why a short online test can never be the last word on a score this low.
Short answer
An IQ of 59 is well below average. It is higher than about 0.31% of people, which puts it at the 0.31 percentile. About 1 in 320 people score 59 or lower, and the WAIS-IV labels it Extremely Low (69 and below). It is 2.73 standard deviations below the mean of 100.
Specimen · IQ 59
59IQ
- Classification
- Extremely Low
- Percentile
- 0.31
- Rarity
- 1 in 320
- z-score
- −2.73
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| Percentile | 0.31 |
| Share scoring 59 or lower | 0.31% (about 1 in 320) |
| Out of 1,000 people | about 3 at or below |
| Standard deviations from the mean (z) | -2.73 |
| WAIS-IV classification | Extremely Low (69 and below) |
| Same percentile, SD 16 scale | 56 |
| Same percentile, SD 24 scale | 34 |
What an IQ of 59 means on the scale
Modern IQ tests report a deviation IQ: scores are standardized so the mean is 100 and the standard deviation is 15 within each age group (Wikipedia: Intelligence quotient). On that scale 59 is 2.73 standard deviations below the mean. It is outside the 70 to 130 range that holds about 95% of people, but inside the 55 to 145 range that holds about 99.7%. (the 68-95-99.7 rule)
In a room of 30 people your age, fewer than 1 (about 1 in every 319 groups of 30) would be expected to score 59 or lower. Put another way, about 100 out of every 100 people score above 59.
The Extremely Low band: 69 and below
Extremely Low is the WAIS-IV label for scores of 69 and below, more than two standard deviations under the mean (Wikipedia: IQ classification). From the normal curve, about 2.1% of people score in this range. Scores near 55 are close to three standard deviations below the mean, the edge of the range that holds about 99.7% of people.
A score this low from a short online test should be treated as unreliable. Misreading the instructions, skipping items, running out of time or testing on a phone can all produce it. If you have real questions about a learning or intellectual disability, for yourself or someone you care for, a licensed psychologist can give a full standardized assessment.
Where 59 sits inside the band
59 is 10 points below the top of the Extremely Low band (69). Of the people who score in this band, about 13% score below 59, so it is near the bottom of the group that shares its label.
Clinical IQ scores carry measurement error of around plus or minus 5 points at 95% (Wechsler, 2008). A measured 59 is consistent with a true score anywhere from 54 to 64, which is the 0.11 to 0.82 percentile. That whole range stays inside the Extremely Low band, so the label is the most stable part of the result. A short online test has a wider range than a clinical one, so read any single number as the middle of a span.
What an IQ of 59 does and does not predict
Only a full clinical assessment, not one number from one session, can say what a score in this range means for a particular person.
Across large groups, the links are real. General intelligence at age 11 correlated 0.81 with exam results at 16 in about 70,000 English children (Deary, Strand, Smith & Fernandes, 2007), a review of 85 years of workplace research put the link with job performance at 0.51 (Schmidt & Hunter, 1998), and a 2007 meta-analysis found correlations of about 0.56 with education and 0.23 with income (Strenze, 2007). Those describe tendencies across many people. None of them let anyone predict an individual life from one number. The guide to what IQ predicts explains what a correlation of that size means.
Same score, different tests
Older Stanford-Binet forms used a standard deviation of 16, and the Cattell Culture Fair III scale uses 24 (Wikipedia: IQ classification). The same percentile as 59 on a standard-deviation-15 test reads as about 56 on the first and 34 on the second, so check which scale a number is on before comparing scores from different tests.
Nearby scores
| IQ | Percentile | Rarity | Classification |
|---|---|---|---|
| IQ 56 | 0.17 | 1 in 600 | Extremely Low |
| IQ 57 | 0.21 | 1 in 480 | Extremely Low |
| IQ 58 | 0.26 | 1 in 390 | Extremely Low |
| IQ 60 | 0.38 | 1 in 260 | Extremely Low |
| IQ 61 | 0.47 | 1 in 210 | Extremely Low |
| IQ 62 | 0.56 | 1 in 180 | Extremely Low |
| IQ 70 | 2.3 | 1 in 44 | Borderline |
IQ 58 · IQ 60 · every score on the IQ chart · IQ percentile calculator · the seven classification bands
Sources
- Intelligence quotient. Wikipedia. en.wikipedia.org/wiki/Intelligence_quotient
- IQ classification. Wikipedia. en.wikipedia.org/wiki/IQ_classification
- 68-95-99.7 rule. Wikipedia. en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule
- Wechsler, D. (2008). WAIS-IV Technical and Interpretive Manual. Pearson.
- Deary, I. J., Strand, S., Smith, P., & Fernandes, C. (2007). Intelligence, 35(1), 13-21. doi.org/10.1016/j.intell.2006.02.001
- Schmidt, F. L., & Hunter, J. E. (1998). Psychological Bulletin, 124(2), 262-274. doi.org/10.1037/0033-2909.124.2.262
- Strenze, T. (2007). Intelligence, 35(5), 401-426. doi.org/10.1016/j.intell.2006.09.004