Tech Freedom Circle

Dec 18, 2025 · Interview Experience

How to Calculate P99 (99th Percentile) and Choose the Right Latency Line for Interviews

This article explains why the 99th percentile (P99) is a critical performance metric, how to compute it efficiently with histogram, HDR Histogram and T‑Digest techniques, compares P90 vs P99, and shows how to answer interview questions about latency monitoring and related metrics.