Jitter
The variation in latency from packet to packet.
Definitions only — a term explained here is not a service we sell.
Jitter is the variation in delay between packets on the same path; for IP it is standardized as packet delay variation (ITU-T Y.1540, IETF RFC 3393). A stream with a stable average but a wide spread arrives unevenly, and real-time applications feel that spread.
Why it matters
Voice and video buffer to absorb jitter. When the variation exceeds the buffer, the application drops or delays packets, so a path with a good average can still sound bad.
A delay distribution
| Value | Zone | What it means |
|---|---|---|
| p50 | 40 ms | Typical packet |
| p95 | 180 ms | Slow tail |
| p95 − p50 | 140 ms | Variation |
Illustrative example; not a measurement of our network.
Text description
The strip plots two points from a delay distribution. The spread between the typical packet and the slow tail is one illustrative way to read delay variation; it is not the definition. A single average hides that spread.
What to check
Ask for percentiles over a window, not one average. Measure at the application's packet rate, because jitter on a ping is not jitter on a voice stream. The latency term and the packet loss term cover the related failures.