An IQ score of 78 falls into the Borderline range on the standard intelligence scale (mean = 100, standard deviation = 15). This score is below the typical range but within the normal distribution; often compensated by skill, experience, and practice.
What an IQ of 78 means
78 is a score about 1 person in 14 would reach or fall below. Among people who have taken our free IQ test, it is far less common than in the general population: in our April to October 2026 data, only 5 of 3,834 people scored exactly 78. That is not because people who take online tests are cleverer than average; it is because they are a self-selected group, typically curious about puzzles and comfortable with screens. Population percentiles and the spread of our own test-takers answer two different questions, and both are shown on this page.
Where does an IQ of 78 rank?
On a standardized IQ test, a score of 78 places you higher than approximately 7.1% 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 | 78 |
| Classification | Borderline |
| Percentile | 7.1% |
| Rarity (out of 1,000) | ~929 in 1,000 score this high or higher |
| Standard deviations from mean | -1.47 |
IQ 78 in numbers
- About 7.1% of people score below 78, and 92.9% score higher.
- In a room of 100 randomly chosen adults, about 93 would score 78 or higher.
- Another 2 points would move this score into the Low Average band, which starts at 80.
- Even on professionally administered tests a single result has a margin of error of about five points either way, so a measured 78 is best read as somewhere between 73 and 83.
On our free IQ test
Of the 3,834 people who completed our free IQ test between April and October 2026, 5 scored exactly 78 and 99.9% 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 78?
A score of 78 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 78
Scores between 70 and 90 are within the normal distribution but below the population mean. Many people in this range thrive in their careers and relationships — IQ is only one dimension of ability. Domain-specific skills, conscientiousness, practice, and social intelligence all contribute significantly to real-world outcomes.
IQ 78 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 78 considered good?
An IQ of 78 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 78 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 78?
An IQ of 78 corresponds to the 7.1th percentile on the standard bell curve — meaning it is higher than about 7 out of every 100 people.