Tool · Deviation IQ scale
IQ percentile calculator
Enter an IQ score to see the percentile it represents on the standard deviation IQ scale. The calculation uses mean 100 and standard deviation 15, which is how most modern tests report results.
Reference
Common IQ scores and percentiles
Use this table to quickly look up where a score sits on the curve.
| IQ score | Percentile | Rough meaning |
|---|---|---|
| 70 | 2.3 | Far below average |
| 85 | 15.9 | Below average |
| 100 | 50.0 | Average |
| 115 | 84.1 | Above average |
| 130 | 97.7 | Far above average |
| 145 | 99.9 | Far above average |
How it works
From score to percentile
The calculation is based on the normal distribution behind the deviation scale.
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. To find a percentile, the calculator converts the score to a z-score — how many standard deviations it is from the mean — and then finds the area under the bell curve below that point.
For example, an IQ of 115 is one standard deviation above the mean, so it sits at about the 84th percentile. An IQ of 85 is one standard deviation below, at about the 16th percentile.
This calculator gives the percentile for a single score. For a realistic assessment, you also need a confidence interval. A score of 115 with a wide interval might really represent anything from 105 to 125.
Limits
What this calculator cannot tell you
A percentile is only meaningful if the score itself is reliable. A single online test with sixteen items can only estimate your true score within a wide band. The percentile for the midpoint of that band is not the same as the percentile for your actual ability.
Also, percentiles assume the test was properly normed. Different tests use different norms, and online samples are not random. Treat this calculator as an educational tool, not a clinical result.
Keep reading
- IQ test: how scoring worksThe deviation scale, item scoring, and why the result is a range.
- Free IQ testA 16-question test with an honest score range, no account needed.
- Online IQ test: what to expectHow online testing differs from a supervised clinical assessment.
- Abstract reasoning testRule-finding puzzles with no words or numbers involved.
- Verbal reasoning testAnalogies and relationships between words and ideas.
- Matrix reasoning testPractice the grid-pattern items used on most modern tests.
- What is a good IQ score?What the numbers mean, and what they cannot tell you.
- Average IQ scoreWhy 100 is the middle of the scale and how national averages work.
- IQ score range chartFrom below average to genius, with percentiles for each band.
See your own percentile
Sixteen free questions, about eight minutes, and a score range with your percentile at the end.
Start the free testNo card required. No email needed to see your first score.