An IQ score of 45 falls into the Extremely Low range on the standard intelligence scale (mean = 100, standard deviation = 15). This score is significantly below the population average and usually associated with profound cognitive challenges.
What an IQ of 45 means
45 is a score that the bell curve predicts for roughly 1 person in 8,100. Real populations, though, contain more people at this level than the curve suggests. Researchers have known since the 1930s that the low end of the distribution has an excess: alongside the ordinary spread of scores, specific genetic and medical conditions add a second, smaller group with lower scores. This is one reason why statistical rarity and clinical prevalence are not the same thing at the low end. For an individual result of 45 from an online test, though, the much more common explanation is an attempt that was not completed under normal conditions.
Where does an IQ of 45 rank?
On a standardized IQ test, a score of 45 places you higher than approximately 0.0% of the population, which means most people score above this level. Intelligence scores follow a normal distribution — most people cluster near 100, and scores taper off sharply toward both extremes.
| Metric | Value |
|---|---|
| IQ score | 45 |
| Classification | Extremely Low |
| Percentile | 0.0% |
| Rarity (out of 1,000) | ~1000 in 1,000 score this high or higher |
| Standard deviations from mean | -3.67 |
IQ 45 in numbers
- About 0.0% of people score below 45, and 100.0% score higher.
- Another 10 points would move this score into the Very Low band, which starts at 55.
- Even on professionally administered tests a single result has a margin of error of about five points either way, so a measured 45 is best read as somewhere between 40 and 50.
On our free IQ test
None of the 3,834 people who completed our free IQ test between April and October 2026 scored exactly 45; 100.0% scored higher. People who choose to take an online IQ test are not a random sample of the population (our average is 114.5), so this shows where a score sits among other test-takers, not among everyone. More in our 2026 data study.
Which IQ tests produce a score of 45?
A score of 45 can be produced by any standardized intelligence test that uses the mean = 100, SD = 15 scale. The most widely used tests include:
- Wechsler Adult Intelligence Scale (WAIS) — clinical gold standard for adults.
- Stanford-Binet Intelligence Scales — oldest continuously-used intelligence test.
- Mensa admissions test — used by the Mensa society for membership selection.
- Cattell-Horn-Carroll (CHC) tests — most theoretically grounded modern framework.
- Our free IQ test — instant online estimate with the same scaling.
How to interpret an IQ score of 45
An IQ score below 70 is sometimes used as one criterion in assessments for intellectual disability, but no modern diagnosis relies on a single score. Clinical diagnosis also requires evidence of adaptive-functioning limitations and a comprehensive evaluation by a licensed psychologist. If you're researching a score in this range for yourself or someone you care about, a professional assessment is the right next step.
IQ 45 in Context
| IQ Range | Classification | Population % |
|---|---|---|
| Below 70 | Extremely Low | ~2.2% |
| 70–79 | Borderline | ~6.7% |
| 80–89 | Low Average | ~16.1% |
| 90–109 | Average | ~50% |
| 110–119 | High Average | ~16.1% |
| 120–129 | Superior | ~6.7% |
| 130+ | Gifted / Very Superior | ~2.2% |
Factors That Influence Your Score
Your IQ score reflects a combination of genetic potential and environmental influences including education, nutrition, health, and the testing conditions themselves. Factors like fatigue, anxiety, unfamiliarity with the test format, and even the time of day can all affect performance. A single test score should be viewed as an estimate, and scores can vary by several points between testing sessions.
Nearby scores
Compare the major IQ tests
Which test produces the most accurate score depends on what you're trying to measure. These head-to-head comparisons break down the differences:
- WAIS vs Stanford-Binet — the two clinical heavyweights compared.
- Mensa vs WAIS — entry-test speed vs full clinical assessment.
- Stanford-Binet vs Mensa — which one actually gets you into Mensa.
- CHC vs Wechsler — modern cognitive framework vs the classic.
- Raven vs Cattell — non-verbal alternatives for cross-cultural testing.
Further reading
- What is a good IQ score?
- What does your IQ score mean?
- Average IQ by age
- Mensa requirements
- IQ test types compared
Want to find out your IQ score?
Take a free, comprehensive cognitive assessment modeled on clinical IQ tests.
Take the Free IQ TestFrequently asked questions
Is IQ 45 considered good?
An IQ of 45 is below the population average, but IQ is a narrow measure — domain-specific skills, experience, and effort matter at least as much as raw score in real-world outcomes.
Can an IQ of 45 change over time?
IQ scores are relatively stable in adulthood but can shift modestly with education, engagement, sleep, and health. Short-term factors like stress and fatigue can move a single test result by 5–10 points in either direction — which is why we recommend comparing results across multiple sessions rather than reading too much into any single score.
What percentile is IQ 45?
An IQ of 45 corresponds to the 0.0th percentile on the standard bell curve — meaning it is higher than about 0 out of every 100 people.