IQ 100
What does an IQ of 100 mean?
The middle of the scale, by design. Here is what that means, how wide "average" really is, and what a score of 100 does and does not tell you.
Short answer
An IQ of 100 is exactly average. It sits at the center of the bell curve, so about half of people score higher and half score lower. The WAIS-IV labels it Average, the band from 90 to 109 that holds about 49% of people.
Specimen · IQ 100
100IQ
- Classification
- Average
- Percentile
- 50
- Rarity
- 1 in 2
- z-score
- 0.00
Curious where you would land? IQ Octopus estimates your IQ from 25 visual puzzles in about 12 minutes.
| Percentile | 50 |
| Share scoring 100 or higher | 50% (about 1 in 2) |
| Out of 1,000 people | about 500 at or above |
| Standard deviations from the mean (z) | +0.00 |
| WAIS-IV classification | Average (90 to 109) |
| Same percentile, SD 16 scale | 100 |
| Same percentile, SD 24 scale | 100 |
What an IQ of 100 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 100 is exactly at the mean. It is the mean of the scale, the point the whole curve is built around.
In a room of 30 people your age, about 15 would be expected to score higher than you and about 15 lower.
The Average band: 90 to 109
Average covers 90 to 109 on the WAIS-IV scale (Wikipedia: IQ classification) and is the largest band by far: about 49% of people score in it. Half of everyone tested lands within this 20-point stretch.
The band is centered on 100, the mean of the scale by construction (Wikipedia: Intelligence quotient). A score of exactly 100 means you did as well as the typical person your age in the test sample. Within this band, differences of a few points are smaller than the error of any test, so 95 and 105 are best read as the same kind of result.
Where 100 sits inside the band
100 is 10 points above the floor of the Average band (90) and 9 points below its ceiling (109). Of the people who score in this band, about 49% score below 100.
Clinical IQ scores carry measurement error of around plus or minus 5 points at 95% (Wechsler, 2008). A measured 100 is consistent with a true score anywhere from 95 to 105, which is the 36.9 to 63.1 percentile. That whole range stays inside the Average 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 100 does and does not predict
An average score means your reasoning on these puzzles matched the typical person your age. It leaves plenty of room for strengths the test does not measure, from knowledge and skills to persistence.
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 100 on a standard-deviation-15 test reads as about 100 on the first and 100 on the second, so check which scale a number is on before comparing scores from different tests.
Nearby scores
| IQ | Percentile | Rarity | Classification |
|---|---|---|---|
| IQ 85 | 15.9 | 1 in 6 | Low Average |
| IQ 90 | 25.2 | 1 in 4 | Average |
| IQ 95 | 36.9 | 1 in 3 | Average |
| IQ 97 | 42.1 | 1 in 2 | Average |
| IQ 98 | 44.7 | 1 in 2 | Average |
| IQ 99 | 47.3 | 1 in 2 | Average |
| IQ 101 | 52.7 | 1 in 2 | Average |
| IQ 102 | 55.3 | 1 in 2 | Average |
| IQ 103 | 57.9 | 1 in 2 | Average |
| IQ 105 | 63.1 | 1 in 3 | Average |
| IQ 110 | 74.8 | 1 in 4 | High Average |
| IQ 115 | 84.1 | 1 in 6 | High Average |
IQ 99 · IQ 101 · 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