IQ Score Chart - What Each Range Actually Means

The IQ score scale at a glance

Modern IQ tests use a standardized scale where the population mean is set to 100 and the standard deviation (SD) is 15. This is the convention adopted by the WAIS-IV, Stanford-Binet 5, WISC-V, RIAS, and nearly every other modern battery. Older tests sometimes used different scales (SD=16 for early Stanford-Binet, SD=24 for the Cattell III-B), which is why historical scores cannot be compared directly.

On the modern SD=15 scale, score ranges fall into well-defined bands:

Why these specific cutoffs?

The boundaries come from the normal distribution mathematics, not from clinical decisions about what "gifted" or "average" should mean. With SD=15:

• 1 SD above mean (115): 84th percentile - about 16% of people score higher
• 2 SDs above mean (130): 98th percentile - the conventional threshold for "gifted"
• 3 SDs above mean (145): 99.87th percentile - about 1 in 1,000
• 1 SD below mean (85): 16th percentile - below this is "low average"
• 2 SDs below mean (70): 2.3rd percentile - the conventional threshold for intellectual disability when paired with adaptive function deficits

The labels (gifted, superior, average, etc.) are conventional but vary slightly between test publishers. The percentile rank is more meaningful and is what should drive any interpretation.

Confidence intervals - why a single score is never the whole story

Every IQ test has measurement error. The WAIS-IV reports its standard error of measurement (SEM) as about 2.5 IQ points. That means a measured score of 120 corresponds to a 95% confidence interval of roughly 115 to 125 - your "true" IQ could fall anywhere in that range.

Online tests have larger SEMs - typically 5 to 8 IQ points, depending on test length and item quality. A 60-question online IQ test might give a 95% confidence interval of plus or minus 10 to 15 IQ points around the measured score. This is why repeat-testing produces apparently different scores even when ability is unchanged.

The practical implication: a single score should always be reported as a range. "Your IQ is approximately 120, with a 95% probability of being between 110 and 130" is honest. "Your IQ is 120" is technically incorrect.

Different IQ tests, different scales

If you have taken IQ tests from different eras or different publishers, the scores are not directly comparable:

What IQ scores do NOT measure

The chart above is a reference for cognitive test performance - not a definition of human worth, success, or potential. IQ specifically does not measure:

• Practical wisdom or judgment - the ability to make good decisions in messy real-world situations
• Emotional intelligence - reading others, regulating your own emotions, managing relationships
• Creativity and originality - weakly correlated with IQ above the 120 range
• Conscientiousness and grit - arguably better predictors of life outcomes than IQ
• Domain expertise - you can have a high IQ and know nothing about, say, music theory or carpentry
• Curiosity, openness, motivation - all strong predictors of intellectual achievement independent of IQ

Many of the most consequential cognitive traits are not measured by any IQ test. A high IQ is a useful tool; it is neither necessary nor sufficient for a meaningful life.

How to interpret your score honestly

If you have taken our full IQ test or another online assessment:

1. Treat the score as a wide range, not a point estimate. Add and subtract 10-15 from your measured score for an honest range.
2. Look at the subscores, not just the composite. A composite of 120 made of 130/130/110/110 means something different than 120/120/120/120.
3. Compare to your test conditions. Were you tired, stressed, distracted? Repeat under better conditions before drawing conclusions.
4. Do not over-interpret. A single score is a snapshot of one cognitive style on one day. It does not determine your future or define your potential.