IQ by percentile
The IQ score at each common percentile, from the top 0.01% to the bottom 1%. Every number is computed from the normal curve, on the three scales tests actually use.
Short answer
On the standard IQ scale (mean 100, standard deviation 15), the top 1% starts at about 135, the top 2% (the Mensa line) at about 131, the top 10% at about 119 and the median is 100. On scales with standard deviation 16 or 24 the same percentiles print as higher numbers above 100.
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| Percentile | SD 15 | SD 16 | SD 24 | 1 in |
|---|---|---|---|---|
| Top 0.01% IQ (99.99th) | 155.8 | 159.5 | 189.3 | 10,000 |
| Top 0.1% IQ (99.9th) | 146.4 | 149.4 | 174.2 | 1,000 |
| Top 0.5% IQ (99.5th) | 138.6 | 141.2 | 161.8 | 200 |
| Top 1% IQ (99th) | 134.9 | 137.2 | 155.8 | 100 |
| Top 2% IQ (98th) | 130.8 | 132.9 | 149.3 | 50 |
| Top 3% IQ (97th) | 128.2 | 130.1 | 145.1 | 33 |
| Top 5% IQ (95th) | 124.7 | 126.3 | 139.5 | 20 |
| Top 10% IQ (90th) | 119.2 | 120.5 | 130.8 | 10 |
| Top 15% IQ (85th) | 115.5 | 116.6 | 124.9 | 7 |
| Top 20% IQ (80th) | 112.6 | 113.5 | 120.2 | 5 |
| Top 25% IQ (75th) | 110.1 | 110.8 | 116.2 | 4 |
| Top 30% IQ (70th) | 107.9 | 108.4 | 112.6 | 3 |
| Top 40% IQ (60th) | 103.8 | 104.1 | 106.1 | 3 |
| Median IQ (50th) | 100.0 | 100.0 | 100.0 | 2 |
| Bottom 25% IQ (25th) | 89.9 | 89.2 | 83.8 | 4 |
| Bottom 20% IQ (20th) | 87.4 | 86.5 | 79.8 | 5 |
| Bottom 10% IQ (10th) | 80.8 | 79.5 | 69.2 | 10 |
| Bottom 5% IQ (5th) | 75.3 | 73.7 | 60.5 | 20 |
| Bottom 2% IQ (2nd) | 69.2 | 67.1 | 50.7 | 50 |
| Bottom 1% IQ (1st) | 65.1 | 62.8 | 44.2 | 100 |
“Top” rows give the score where the top tail starts; “bottom” rows give the score where the bottom tail ends. “1 in” is how many people it takes, on average, to find one in that tail.
Why three scales
Modern tests such as the Wechsler scales and the Stanford-Binet Fifth Edition use a standard deviation of 15 (Wikipedia: Intelligence quotient). Older Stanford-Binet forms used 16, and the Cattell Culture Fair III scale uses 24 (Wikipedia: IQ classification). A percentile is the same on all three; only the printed number changes. That is why Mensa UK quotes 148 on Cattell III B and 132 on the Culture Fair test for the same 98th percentile (Mensa UK).
Reading a percentile
A percentile is the share of people your age expected to score below you. It is not the share of questions you got right. Near the middle, a few points move the percentile a lot; out in the tails the same few points barely move it. For any other number, use the percentile to IQ converter or the IQ percentile calculator.
Free tools: IQ percentile calculator · Percentile to IQ converter · IQ score chart
Related
- No. 01Top 1% IQAbout 135 on the standard scale. 137 on SD 16, 156 on SD 24.
- No. 02Top 2% IQAbout 131 on the standard scale. 133 on SD 16, 149 on SD 24.
- No. 03Percentile to IQ converterAny percentile to the matching IQ on three common scales.
- No. 04IQ scoresPercentile, rarity and classification for every score.
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