What does an IQ of 138 mean?
At the upper end on the reference scale, at approximately percentile 99.44.
- IQ score
- 138
- Percentile
- 99.44
- At or above
- 0.56%
Normal reference · mean 100 · SD 15. These are calculated values, not observed starp population ranks.
Where 138 sits on the IQ scale
A score of 138 is 38 points above the mean. Dividing by the standard deviation gives (138 − 100) ÷ 15 = 2.53. The normal cumulative distribution converts that standardized position into percentile 99.44.
This is at least two standard deviations above the mean. Only a small upper share of the model lies at or beyond this point. At this end of a scale, the test ceiling, norms and reported uncertainty deserve particular attention.
How common is a score of 138?
Approximately 0.56% of this model lies at or above 138—about 1 in 177. This is a cumulative share, not the chance of scoring exactly 138. A continuous model does not assign a positive probability to one exact value.
Compared with IQ 130, the reference percentile is 1.71 percentage points higher. 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
Compare 133 and 138 or calculate 138 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 138 from 29 correct answers (96.67% 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 138
Is 138 a good IQ score?
138 is above the reference mean of 100. It is a higher score on that scale, but a number alone cannot establish a specific skill profile or predict success.
What percentile is an IQ of 138?
On a normal scale with mean 100 and standard deviation 15, 138 corresponds to approximately percentile 99.44. Around 0.56% of that model lies at or above it. Use an assessment's own norms for an actual reported rank.
Does an IQ of 138 mean 138% 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.