Reaction Time Percentiles Explained
A percentile is a comparison, not a verdict.
TL;DR — Percentiles compare your score to the test's sample, not the global population. The same score can be 60th percentile on one platform and 85th on another — both can be correct.
Percentiles only mean something when you know whose population you are being compared to.
Reference distribution by sample
| Sample | Mean RT | Median RT | 90th percentile |
|---|---|---|---|
| HumanBenchmark visitors | 273 ms | 263 ms | 218 ms |
| SERO desktop visitors | 258 ms | 249 ms | 205 ms |
| Clinical adult norms | 270 ms | 265 ms | 225 ms |
| Esports semi-pro pool | 210 ms | 205 ms | 180 ms |
Why the same player gets different percentiles
A 220 ms score puts you in roughly the 70th percentile of HumanBenchmark, the 55th of SERO's desktop sample, and the 30th of an esports pool. Same speed, three different verdicts — because the comparison group changed.
How to interpret yours honestly
- Compare to a single platform over time, not across platforms.
- Look at your own SD as well as your mean.
- Use the same device and time of day to keep noise low.
- Track the 30-day rolling average, not single sessions.
Common misreadings
- "I am top 1% globally" — usually means top 1% of one test's users.
- "My score dropped 30 ms in a week" — almost always device, sleep or attention drift.
- "My friend is 90th percentile and I am 70th" — meaningless unless on the same platform.
Frequently Asked Questions
Are RT percentiles age-adjusted?
Rarely on web tests. Clinical norms usually are.
Can I compare desktop and mobile percentiles?
No — hardware skew makes the comparison meaningless.
What is a "good" percentile?
Above the median (50th) is normal. Above 80th is fast. Above 95th is exceptional.
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