How 90th Percentile Is Calculated in Reports
Recommended guidance
The 90th percentile is the value below which 90% of measured samples fall. In AIQ reporting, use it to understand typical high-end response time without letting a few extreme outliers dominate the interpretation.
How to interpret it
- If the 90th percentile response time is 2 seconds, 90% of samples completed in 2 seconds or less.
- The remaining 10% were slower than that value.
- Percentiles should be reviewed with average, median, error rate, throughput, and sample count.
- Small sample sizes can make percentile values unstable.
Reporting checklist
- Confirm the metric and transaction represented by the percentile.
- Check whether failed or timed-out samples are included or excluded.
- Compare percentile values only between runs with similar data, load, and environment.
- Use percentiles with charts and logs to identify sustained slowness versus isolated spikes.
Last updated: October 6, 2026