Ping, Jitter and Latency Explained

Speed and latency measure two completely different things, and confusing them is why people buy a faster plan and find their video calls are exactly as bad as before.

Speed is how much data moves per second. Latency — reported as ping — is how long it takes for a single packet to reach a server and come back. A connection can be enormously fast and still feel sluggish, because those are independent properties. Satellite internet is the clearest example: plenty of bandwidth, and a delay long enough to make conversation awkward.

Ping is a round trip measured in milliseconds. It is dominated by physical distance — data travels fast but not instantly, and every router along the way adds a little. A server in the same city might answer in 10 ms; one on another continent will not beat 150 ms no matter what you pay.

One caveat applies to every browser-based test, including ours: the figure includes the distance to the test server, which can be 50 to 100 ms before your own connection is counted at all. Compare results from the same tool over time rather than between different tools.

Jitter is how much your ping varies between one moment and the next. It is the most useful number on a speed test and the one almost nobody looks at.

Here is why it matters. Voice and video are sent as a stream of small packets that need to arrive evenly spaced, because they are played back at a fixed rate. If your ping is a steady 80 ms, the software absorbs it and you never notice. If it swings between 40 ms and 400 ms, packets arrive in bursts, the buffer runs dry, and the call clips words and freezes — even though the average speed and the average ping both look fine.

That is the answer to the most common complaint about home internet: my speed test looks great but my calls keep breaking up. The average was never the problem. The variation was.

In rough order of how often they are the culprit:

• Wi-Fi. Distance, walls and interference from neighbouring networks add both delay and variability. This is the single most common cause, and the easiest to prove.
• Another device saturating the line. A backup or a game update fills the queue, and everything else waits behind it.
• Distance to the server. Unavoidable, and not a fault.
• Peak-hour congestion. Cable is shared locally, so evenings can be measurably worse than mornings.
• The connection type. Fibre has the lowest latency, then cable, then DSL, then mobile, with satellite last by a wide margin.

The diagnostic takes two minutes: run a test over Wi-Fi, then run it again with an Ethernet cable. If ping and jitter improve sharply on the cable, the problem is inside your home and no amount of paying your provider more will fix it.

Use a cable for anything that matters — a call you cannot afford to drop, or competitive gaming. If that is not practical, move closer to the router and use the 5 GHz band rather than 2.4 GHz, which is slower and shares its airspace with every neighbour and microwave in range.

Beyond that: pause backups and downloads before an important call, and if your router supports QoS, prioritise voice and video traffic. Replacing an old router helps if it predates Wi-Fi 5. What will not help is buying a faster plan, because more bandwidth does nothing for a latency problem — which is exactly the mistake the distinction at the top of this page exists to prevent.