What does an IQ of 70 mean?
Below the central range on the reference scale, at approximately percentile 2.28.
- IQ score
- 70
- Percentile
- 2.28
- At or above
- 97.72%
Normal reference · mean 100 · SD 15. These are calculated values, not observed starp population ranks.
Where 70 sits on the IQ scale
A score of 70 is 30 points below the mean. Dividing by the standard deviation gives (70 − 100) ÷ 15 = -2. The normal cumulative distribution converts that standardized position into percentile 2.28.
This is below the central 85–115 interval of the reference scale. A single result does not provide a diagnosis or determine what someone can learn. The original report, testing conditions and purpose matter when interpreting it.
How common is a score of 70?
Approximately 2.28% of this model lies at or below 70—about 1 in 44. This is a cumulative share, not the chance of scoring exactly 70. A continuous model does not assign a positive probability to one exact value.
Compared with IQ 85, the reference percentile is 13.59 percentage points lower. Equal IQ-point gaps do not create equal percentile gaps: the middle of the bell curve contains more area than its ends.
Compare nearby scores
| IQ score | Percentile | At or above |
|---|---|---|
| 70 | 2.28 | 97.72% |
| 75 | 4.78 | 95.22% |
Compare 70 and 75 or calculate 70 on another scale. A small difference between test results is not automatically a meaningful change.
How this relates to starp
starp's current 30-question scoring map produces 70 from 15 correct answers (50% correct). That accuracy percentage is different from the normal-model percentile above. The scoring map was calibrated with 12,700 simulated assessments; it is not population norming.
See the scoring method and how raw scores differ from IQ estimates.
Questions about IQ 70
Is 70 a good IQ score?
70 is below the reference mean of 100. It should be interpreted in the context of the test, rather than as a verdict on a person's abilities or future.
What percentile is an IQ of 70?
On a normal scale with mean 100 and standard deviation 15, 70 corresponds to approximately percentile 2.28. Around 97.72% of that model lies at or above it. Use an assessment's own norms for an actual reported rank.
Does an IQ of 70 mean 70% correct?
No. IQ is a scaled score. Percentage correct depends on the questions and scoring rules; percentile describes a relative position. These three quantities are not interchangeable.
Method: NIST's normal-distribution formula. Percentiles here are calculated reference values, not observed starp population ranks. About starp scoring.