What is jitter?
Every request your device sends takes a slightly different amount of time to come back. Jitter is how much that time changes from one request to the next. If your ping is 40 ms, then 42 ms, then 39 ms, jitter is low and the connection feels smooth. If it's 40 ms, then 180 ms, then 35 ms, jitter is high, and anything happening in real time suffers.
Video calls, voice chat and online games send a steady stream of small packets and play them back as they arrive. They can cope with a constant delay by buffering a little, but packets that arrive unevenly make audio go robotic, video freeze for a moment, and game characters rubber-band across the screen. That's why a connection can pass a speed test, show a decent ping, and still give you terrible calls.
How this jitter test works
The test sends 60 small DNS-over-HTTPS requests to Google's public DNS service (8.8.8.8), about half a second apart, after one warm-up request that opens the connection and isn't counted. If Google can't be reached, the whole run uses Cloudflare's 1.1.1.1 instead. The chart draws each round trip as it happens; the dashed line is the median, and any red marks are requests that failed or took longer than three seconds.
Jitter is calculated as the average absolute difference between consecutive measurements. That's the same idea as the jitter figure in RTP, the protocol most voice and video calls use, without the smoothing. Alongside it you get the biggest jump between two consecutive measurements, the share of smooth changes (moves of less than 10 ms), your typical ping and any failed requests.
What is a good jitter?
| Jitter | Video & voice calls | Online gaming |
|---|---|---|
| Under 8 ms | Excellent | Excellent |
| 8–15 ms | Good | Fine for most games |
| 15–30 ms | Usable, occasional glitches | Noticeable in fast-paced games |
| Over 30 ms | Robotic audio, frozen video | Rubber-banding and lag spikes |
Streaming services like Netflix and YouTube buffer several seconds ahead, so they tolerate far more jitter. Up to 50 ms is fine, and even 100 ms rarely causes a visible problem as long as requests aren't failing.
Jitter vs ping vs packet loss
Ping is the delay itself. Jitter is how much the delay varies. Packet loss is data that never arrives. All three affect real-time apps, but jitter is the one people most often miss, because speed tests barely mention it. For a quick check of all three in 10 seconds, use the ping test. Use this jitter test when calls or games feel unstable and you want to see the pattern over a longer window.
Test it under load: bufferbloat
Many connections look perfectly steady when nothing else is happening, and fall apart as soon as someone starts a big download, uploads photos to the cloud, or a game console installs an update. The router queues so much traffic that every other request waits behind it. That's called bufferbloat, and it's one of the most common hidden causes of bad video calls at home.
To check for it, run the jitter test twice: once with nothing else using the connection, and once while a large download or upload is running on another device. If jitter and the biggest jump shoot up during the second run, your router isn't managing its queues well. Routers with Smart Queue Management (SQM) or a good QoS setting fix this almost completely.
How to reduce jitter
- Use Ethernet for calls and gaming. WiFi is the single biggest source of jitter at home, especially on the crowded 2.4 GHz band. If you must use WiFi, use 5 GHz and sit closer to the router. The WiFi drop test can tell you whether your WiFi is the weak link.
- Pause heavy traffic during calls. Cloud backups, game downloads and 4K streams on other devices fill the router's queue.
- Turn on SQM or QoS if your router supports it, and prioritise your work laptop or console.
- Restart and update the router. Older firmware and routers that have been running for weeks can queue traffic badly.
- Check the time of day. Jitter that only appears in the evening points to congestion in your provider's network. Our guide to remote work internet requirements covers what to ask your ISP for.
One test is a snapshot
Jitter problems often come and go: a neighbour's network on the same WiFi channel, evening congestion, a backup that runs at 8pm. If the test looks fine now but calls were bad earlier, leave the free 24/7 monitor running. It measures your connection every second and timestamps every latency spike and outage, so you can see exactly when things go wrong.
Calls only break up sometimes? Let the monitor record every spike with a timestamp.
Start the free 24/7 monitorJitter test FAQ
What is a good jitter?
Under 15 ms is good for video calls and voice, and under 8 ms is ideal for competitive gaming. Between 15 and 30 ms calls usually still work with occasional glitches; above 30 ms real-time apps struggle. Streaming tolerates much more.
What is the difference between ping and jitter?
Ping is how long a round trip takes; jitter is how much that time changes from one round trip to the next. Apps can adjust to a steady delay, but not to a jumpy one.
What causes high jitter?
WiFi interference or weak signal, other devices uploading or downloading at the same time (bufferbloat), a congested ISP network at busy times, and routers that queue traffic poorly. Satellite and mobile connections also tend to have higher jitter.
How do I reduce jitter?
Use Ethernet, pause heavy transfers during calls, enable SQM or QoS on your router, use the 5 GHz WiFi band, and test at different times of day to spot ISP congestion.
How does this jitter test measure jitter?
It times 60 DNS-over-HTTPS requests about half a second apart and averages the absolute difference between consecutive round-trip times, the same idea as RTP jitter without smoothing.
Why should I run the jitter test during a download?
Because many connections are only jumpy under load. Testing once idle and once during a large download or upload shows whether you have bufferbloat.