IQ 78: what it means, percentile and how rare it is
An IQ score of 78 is higher than about 7.1% of people, which puts it in the 7th percentile. Roughly 1 in 14 people score lower than 78. On the WISC-V it is classified as Very Low.
- Percentile
- 7th
- Higher than
- 7.1%
- People scoring lower
- 1 in 14
- WISC-V classification
- Very Low
What does an IQ of 78 mean?
- In a group of 100 people, about 7 would score lower than 78.
Scores from 70 to 79 are labelled Very Low on the WISC-V; older editions such as the WAIS-IV called this range Borderline. About 7% of people score here.
Many people with scores in this range finish school, work and live independently, though they may find abstract, fast-paced or heavily academic tasks harder and benefit from extra time, practical teaching and step-by-step explanations.
This is also where measurement error matters most. With a margin of about ±5 points, a true score near 75 could fall on either side of 70, which is why professionals never rely on a single number and always look at everyday functioning too.
IQ 78 on other scales and tests
Different tests spread scores differently. The same rank as an IQ of 78 on an SD-15 test gives these numbers elsewhere:
| Scale | Equivalent score | Classification |
|---|---|---|
| SD 15: WISC-V, WAIS, Stanford-Binet 5 | 78 | Very Low |
| WAIS-IV (older label) | 78 | Borderline |
| Stanford-Binet 5 | 78 | Borderline impaired or delayed |
| SD 16: older Stanford-Binet, Cattell Culture Fair | 77 | – |
| SD 24: Cattell III B | 65 | – |
How precise is an IQ score of 78?
No test measures IQ exactly. On individually administered tests such as the WAIS, the full-scale score comes with a 95% confidence interval of roughly ±5 points, so a result of 78 is best read as "probably somewhere between 73 and 83". Scores can also shift a few points between different tests or after a few years.
Online tests, including ours, are self-assessments. They are useful for curiosity and practice, but they are not a substitute for an assessment by a psychologist.
IQ scores near 78
Check another IQ score
For example 98 for the top 2%.
- Percentile
- 7th
- Higher than
- 7.1%
- People scoring lower
- 1 in 14
- Classification (WISC-V)
- Very Low
IQ 78: frequently asked questions
Is an IQ of 78 good?+
It is below the average of 100. An IQ of 78 is higher than about 7.1% of people and falls in the Very Low range. A single score, especially from an online test, says little on its own; a psychologist would look at much more than one number.
What percentile is an IQ of 78?+
An IQ of 78 is in the 7th percentile on a scale with mean 100 and standard deviation 15. It is higher than about 7.1% of people and lower than about 92.9%.
How rare is an IQ of 78?+
Roughly 1 in 14 people score lower than 78. In a group of 1,000 people you would expect about 71 to score lower.
Does an IQ of 78 mean intellectual disability?+
No, not on its own. DSM-5-TR describes the intellectual criterion as roughly two standard deviations below the mean including measurement error (about 65 to 75), but a diagnosis also requires real difficulties with everyday adaptive skills that began during development, assessed by a qualified professional. An online score can never establish it.