What does an IQ of 81 mean?
Below the central range on the reference scale, at approximately percentile 10.26.
- IQ score
- 81
- Percentile
- 10.26
- At or above
- 89.74%
Normal reference · mean 100 · SD 15. These are calculated values, not observed starp population ranks.
Where 81 sits on the IQ scale
A score of 81 is 19 points below the mean. Dividing by the standard deviation gives (81 − 100) ÷ 15 = -1.27. The normal cumulative distribution converts that standardized position into percentile 10.26.
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 81?
Approximately 10.26% of this model lies at or below 81—about 1 in 10. This is a cumulative share, not the chance of scoring exactly 81. A continuous model does not assign a positive probability to one exact value.
Compared with IQ 85, the reference percentile is 5.6 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
Compare 76 and 81 or calculate 81 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 81 from 18 correct answers (60% 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 81
Is 81 a good IQ score?
81 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 81?
On a normal scale with mean 100 and standard deviation 15, 81 corresponds to approximately percentile 10.26. Around 89.74% of that model lies at or above it. Use an assessment's own norms for an actual reported rank.
Does an IQ of 81 mean 81% 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.