How it's calculated
percentile = Φ((IQ − 100) ÷ 15)
IQ = score, 100 = mean, 15 = standard deviation, z = (IQ − 100)/15, Φ = standard normal CDF. Percentile = share of people scoring below. Reverse: IQ = 100 + 15 × Φ⁻¹(p).
Reference ranges
| IQ score | Percentile | Classification |
|---|---|---|
| 70 | 2nd | Borderline |
| 85 | 16th | Low average |
| 100 | 50th | Average |
| 115 | 84th | High average |
| 130 | 98th | Very superior |
Common questions
What percentile is an IQ of 130?
An IQ of 130 sits at roughly the 98th percentile, meaning about 2 percent of people score higher.
What is the average IQ?
The average IQ is 100 by design, since the test is scaled to a mean of 100 with a standard deviation of 15.