Glossary

p50 latency (median)

p50 latency is the 50th percentile of request durations: half of all requests complete faster than this value, half slower. It represents the experience of the median user under normal load. Because the median is inherently resistant to outliers, it is a poor choice as a sole SLO metric — a system can have an excellent p50 while still subjecting 1% of users to severe latency.

Formula: Sort latencies ascending; median index ≈ ceil(0.50 × n). Pair p50 with p99 or p99.9 for user-facing SLOs.

Last updated: March 2026