What Is Jitter? How It Affects Calls and Games
Jitter is how much your latency changes from one moment to the next. If every message takes about 20 ms to make the round trip, jitter is low. If one takes 15 ms, the next 60 ms and the next 25 ms, jitter is high, even though the average latency might look fine.
Why steady delay matters
Real-time apps (voice calls, video calls, online games and cloud gaming) send a constant stream of small packets and expect them to arrive at an even pace.
- Calls: the app has to hold back incoming audio in a small “jitter buffer” to smooth out uneven arrival. The more uneven the delay, the bigger that buffer must be, which adds delay to the conversation. If a packet arrives too late, the audio crackles or drops a syllable.
- Games: uneven delay shows up as rubber-banding, where other players jump around, or as actions that register late.
- Streaming video is much less sensitive. Players buffer several seconds ahead, so moderate jitter is usually invisible.
How jitter is measured
There are several ways to define jitter. Network standards call it “packet delay variation” (RFC 3393). Voice and video protocols use a smoothed estimate (RFC 3550).
SpeedCheckWeb reports jitter as the average change between consecutive latency samples. For example, with samples of 20, 30, 25 and 25 ms, the changes are 10, 5 and 0 ms, so jitter is (10 + 5 + 0) ÷ 3 = 5 ms. Many browser-based tests use this same approach. It is simple to understand and reacts to the “spikiness” that apps actually notice.
Because different tests use different definitions and sample counts, jitter numbers from different tools are not always directly comparable. Compare results from the same test over time instead.
What is a good jitter value?
Rules of thumb, for jitter measured as above to a nearby server:
| Jitter | What to expect |
|---|---|
| Under 5 ms | Excellent and very stable. |
| 5–15 ms | Good for calls and most games. |
| 15–30 ms | Fair: calls may glitch now and then, and competitive games may feel uneven. |
| Over 30 ms | Poor for real-time use; look for the cause. |
Common causes of high jitter
- Wi-Fi interference. Microwave ovens, Bluetooth devices, neighbouring networks on the same channel and thick walls make Wi-Fi delay irregular. This is the most common cause at home.
- A busy connection. When someone uploads or downloads at full speed, queues fill up and empty unevenly. See bufferbloat.
- Mobile and satellite links. Radio conditions change constantly, so delay varies more.
- Power-saving modes. Some laptops and phones put Wi-Fi to sleep between packets, which adds small, irregular delays.
- Overloaded equipment. An old router or a router running hot can process traffic unevenly.
How to reduce jitter
- Use an Ethernet cable for gaming PCs, consoles and work computers. This usually brings the biggest improvement.
- Move closer to the router, or use the 5 GHz or 6 GHz band instead of 2.4 GHz.
- Pause large downloads and uploads during calls and games.
- Turn on Smart Queue Management (SQM) or a similar feature if your router supports it. It keeps queues short when the line is busy.
- Restart and update your router. Firmware updates often fix performance problems.
Run the ping and bufferbloat test before and after each change to see what actually helps.
In short: jitter is uneven latency. Low jitter keeps calls clear and games smooth, and Wi-Fi interference and busy connections are the usual causes.
Sources
- RFC 3393 – IP Packet Delay Variation Metric for IPPM
- RFC 3550 – RTP, A Transport Protocol for Real-Time Applications (interarrival jitter)
Figures from third parties can change; we review guides regularly. See our editorial policy.