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Reviewed score guide

What does an IQ of 120 mean?

On a theoretical mean-100, SD-15 normal model, IQ 120 is 1.33 standard deviations above the mean, approximately the 90.88th percentile, and about 1 in 11 at or above. That calculation does not authenticate a score or replace the test publisher’s norms.

points
Normal-model scale
Percentile90.9thNormal-model estimate
Directional rarityabout 1 in 11at or above
Standard position+1.33σ1.33 SD above the mean
Normal-model bell curve for IQ 120IQ 120 is shown at approximately the 90.88th percentile on a scale with mean 100 and standard deviation 15.557085100115130145120

This is a theoretical normal-distribution conversion, not a test result, diagnosis, confidence interval, or eligibility decision. Official percentiles depend on the exact test, edition, age norms, and score report.

Interpretation

Read the model, then read the test report.

The percentile shown here comes from a smooth normal distribution. A real assessment is normed for a particular test edition, age group, and reference sample. Its score report may provide a different rounded percentile and a confidence interval.

At high scores, apparent precision becomes especially misleading. Test ceilings, measurement error, practice effects, and differences between instruments matter more than extra decimal places.

What this number cannot establish

  • It cannot verify that an online or reported score is genuine.
  • It cannot diagnose giftedness, disability, or any condition.
  • It cannot predict a person’s achievements, values, or future.
  • It does not make scores from different tests interchangeable.